I look at the 200 series as just older designs/technology. I think the specific difference vary by window type/model. What specific windows are you comparing?

I am looking at the double hung tilt window. Exterior white and interior pre-finished white (not vinyl) w/ Low E glass. Colonial grills. Nothing extraordinary. Basic look to the window in standard size approximately 35" wide and 5'6". Thanks for your thoughts

200 series tilt were designed to compete with the vinyl market, that's why the limited sizes. It is a good window if installed correctly. Personally I'd go with the 400's, they just seem to seal better.

I assume you have an Andersen product guide and have looked in there for info' on the tilt-wash windows. Fibrex sills vs. PVC covered wood; fancier weather stripping; Low-E4 (0.32 U-Factor) vs. regular (0.47 U-Factor) glass - from the 2008 book - but maybe things have changed for 2009?

I don't have much more to offer - I have an older, 200 series and just installed a newer, 400 series awning window and then seem to be pretty much the same except for the glass.

The Anderson 400 series are clear Ponderosa pine interiors
and have their high performance glass while the 200 series has just low e glass and the interior is painted white wood.
That is, its' probably fingerjointwood. The paint conceals the the Finger Joint.

The porchguy

Here is a link that might be useful: My Album