If you slice them you should see:

-- pineapple has a single plain pineapple-like yellow flesh.
--Rainbow should be bi color, with streaks of orange/red. Sometimes the streaks are visible on the outside too.

You know that Big Rainbow is a gold/red bicolor, and so is Pineapple, link below, and I've grown them both.

There are close to 300 or so gold/red bicolors known and most look the same. One difference is that the secondary exterior color with a few goes right up to the stem end, an example of that is Mary Reynolds German Bicolor such that the whole fruit is a reddishpink/

The second difference is taste. and that's a minor variable.

I've grown many of this kind and find that they are finicky, one season being sweet and lucious, the next season with the same variety, bland and Mealy. So they appear to be very much influenced by weather in any one season IMO.

And a few are known for consistently low yields, and Mr. Stripey is one of them for the majority of folks who grow it.

Carolyn

Here is a link that might be useful: Pineapple

If there is a meaning in the name, when I hear "PINEAPPLE" tomato, this is what I think of. There are some bi colors that are also carry the name "pineapple". This is just part of the mish mash of naming convention in tomato world. CONFUSING!

Big Rainbow was great producer for me even in a bad year, although taste is not to my liking but then I am yet to find my perfect bicolor...