Ask whoever told you the 'A' series would be better why they would be better?

The main difference is appearance and how the double hungs tilt in. I would look at both in person and operate them and decide if those things are worth the price difference.

Andersen makes two versions of the 400 series: the Tilt-Wash and the Woodwright. They have the same frame but the sash are very different. Tell us what you are considering.

Don’t think the Woodwrights are available with a nail fin.

All Andersen residential windows are available with a nail fin. The 400 Tilt-Wash and the 400 Woodwright have the same PVC clad frame but the Woodwright (below) has a composite clad sash.

Here is the Andersen A series. I suppose it has fiberglass in the frame cladding and Fibrex (PVC & sawdust) in the sash cladding. Andersen doesn't publish much about how their windows are actually constructed.

A SERIES

The 400 Tilt-Wash has the same frame as the Woodwright but it has a wood sash with epoxy paint instead of a cladding.

I would disagree that the main difference between the 400 and the A is appearance and the tilt mechanism (though these are two major differences). They are structurally completely different windows. The 400 Tilt-Wash is a wood window with a vinyl-clad frame. The sash is either coated with a polyester paint (double-hung) or vinyl (other types).

The A-Series is quiet different. The frames are an Andersen product called Fibrex, and the sashes are fiberglass, with very thick wood veneers on the inside. They have additional weather-stripping, and for casements, an additional locking-point. As a result, they are more energy-efficient independent of the glass, as the structural parts are less conductive and their have lower air-infiltration. They also have a higher design pressure rating. I won't go into the various aesthetic differences, but will summarize that that the customization options are much greater. I find them much more attractive both interior and exterior. I also think they will last longer, as there is no wood-core to rot if there's a cladding-failure, and fiberglass is considerably more stable than vinyl.

Personally, I find the 400 series sufficiently unattractive that I would use a quality all-vinyl window before it. But that's subjective.

I was wrong about the Woodwright not available for new construction. I wood agree that there are more differences between the Woodwright and A-Series than I mentioned but I don’t think most homeowners wood know the differences. Since they look very similar, The extra weatherstripping is nice but means little unless you got air infiltration numbers on both which I doubt you do. All the other thermal numbers are near identical across there lines when comparing operating types. The PG ratings are better with A-series but there upgrades kits for the others. The design in regards to rot resistance is a good point but from what I have seen the others hold up very well and the jury is out on the A-Series due to it being a newer design. I would concur the A-Series is better in some regards and maybe in all till I see the ever elusive air infiltration numbers but imo it may not be worth the extra dollars that they command to most consumers.

The infiltration numbers (some - they appear to submit a few sizes for testing) are available, they're just a bit hard to find on the website. Interesting read as the numbers are far more accurate than in the general product guide. Andersen Test Reports

A series casements are all less than .01 cfm/ft2. 400 ranges from .03-.05 depending on size. The double-hungs are roughly the same, and far more variable based on size (most likely width). About .07 and PG50 for a fairly large A-series (40x95). A 45x92 400 tilt-wash is .10 and PG30. The woodright is much worse - A 45x76 unit has infiltration of .16cm/ft2. The woodright is also much harder to open - 38 pound-force as opposed to 20 for a much larger A-series. The A-series casements require 25% less force to open than the 400.

My conclusion is that the A-Series casements are significantly tighter, and the double-hungs are a wash.

I agree that from the interior, the A-Series and Woodwright look pretty similar. I was comparing with the tilt-wash.

I look at the details first and the A Series is disappointing compared to the Woodwright. The tilt-wash is in between the others. Here's why:

The first thing I look at is the sill shape. The 400 series has a strong slope and the best drip and siding notch in the business. (It was once not that way and I was involved in the project that forced Andersen to redesign the sill 40+ years ago.). However, I might be able to live with the A series sill slope if a sub-sill was added below the window; I usually add one anyway.

Second, I look at the position of the sash relative to the nail-fin/face of sheathing. IMO the sash should be at least 3/4" behind the fin in order to provide a strong shadow line at the window head and a traditional appearance instead. For a very modern or light commercial project the negative back-set of the A Series might be acceptable but I would avoid the bug-eyed look for a traditional house.

Third, I look at the width of the frame and sash. At the jambs the A Series is the same as the 400 series but at the head its 3/4" larger which will not be attractive since the sash is so far forward.

So, I would use the Woodwright instead of the A Series and I would consider Marvin's Elevate before using the 400 Tilt-Wash because ... I can scratch the sash paint off with my thumb nail and the new oversized glass stop is butt ugly.

At this juncture Marvin's Elevate/Essential products could be considered.

The Essential is an all-fiberglass version of a vinyl window and is positioned so far in front of the sheathing that it looks bugged-eyed. I believe it only has between-the-glass mullions.

@RES, architect All good points. On my project, I added a sub-sill, and exterior foam insulation, which had the effect of recessing the windows further. I agree that the added height of the check-rail is disappointing.

Unfortunately, there's no such thing as a perfect window. For my project, I wanted features that Marvin only offers in Ultimate (Oak interior, exterior color, high-transparency screens veneered to match the windows, floating SDL spacers), but Ultimate wasn't in the budget. I also was doing almost all casement windows, and found the A aesthetics, both inside and outside, much preferable to the 400 (the welded vinyl corners and the frame/sash interface).

If the project were all double-hungs, I probably would have sucked it up and either done E series or Ultimate, as the wide check-rail would have looked "wrong". I can't imagine why they designed it that way - the marketing fluff claims 'historical accuracy" and then they violated one consistent rule of historical windows. I will say, the work they did to get the lights of paired casements/picture/double-hung to align is very good.

To the OP - Sorry if this has gotten off track. Some additional information such as the type of window you're looking at would be helpful. One design point - when I hear "modern farmhouse" I tend to think of windows being a different color from the trim. If you're doing this, it is important that only the WINDOW SASH be a different color - the frame should match the trim. Most people don't specify this, and it looks wrong. It's a bit tricky to accomplish, as it either means you have to paint the window frames (and this may not work on all materials) or you have to stick with one of your window maker's exterior colors for your trim. If the trim is to be white, that simplifies it some.

Wow! Thank you all for your comments! I have an entirely new vocabulary after reading them :)

We are leaning toward black int/ext casement windows with white trim around them on both inside and outside of the house.

Upon further research, it appears some people have been unhappy with the finished product of the 400 series due to the corners being finished poorly/having a grey color to them compared the the black they should be and Andersen not standing behind the product. In your experience, is this a common problem with Andersen 400 series windows?

The 400 casement is pretty much a vinyl window with a wood interior that mostly hides the sash. the corner welds are noticeable as with most Vinyl windows. Most home owners do not notice this but some do . I really recommend looking at them in person.

If you're doing casements, I would suggest the A or E over the 400. The 400 has vinyl wrapped over the inside of the sash, so vinyl is visible on the inside. The corner welds are somewhat sloppy and can collect dirt. They only have one sash locking point, instead of 2 or 3, and thus are leakier. The sash is pretty much flush with the frame on the outside. The A does have thicker structural components on the sash than the 400, which may be at odds with the "modern farmhouse" look. If this is an issue, the E series or a quality all-vinyl window, such as Sunrise, Softlite or Okna may be a better solution.

I've attached some photos. Please excuse the unfinished painting/staining.

400 Exterior:

A Exterior:

400 Interior:

A Interior:

Appreciate the clarification and the images! I'll need to go take a closer look now that I know specifically what to look for. Thanks again for all of the information/suggestions :)