Hey there Allie!
My family and I visit at least one of those two restaurants every time we do our Disney vacation. In my opinion, T-Rex & RainForest are basically the same restaurant with different themes. Personally, I think they are fun places to eat with good portions but I think it is very standard food (Burgers & Fries) at a premium price.
I kind of hate writing on boards because the other person,
you, can't get the tone of my message. So let me tell you that in the next statement I am just making a general statement and it is nothing against you ... I hate to think that somebody would think I am talking down to them ... I certainly don't want to do that!!!

Just wanna help!
When you eat in a place like RainForest or T-Rex you really aren't paying for the food so much as the ambiance. I mean think about it ... any given eatery in Disney (Or any park for that matter) is very expensive compared to its off property counterpart!
For example,
and this is just my opinion, the Teppan Edo restaurant in EPCOT's Japan Pavilion is a glorified Kobe restaurant. Same idea but I can go off Disney property to Kobe, get more food (Just as yummy), a better show, and pay less for it ... BUT ... I'm not IN Disney so the difference in price is due to ambiance.
Come on, you can get a burger and fries or ribs at almost any eatery and pay A LOT less than Rain or T ... it's all about WHERE you're eating

Which is why I always tell anyone who I happen to be giving advice on a vacation to that IF POSSIBLE eating off property will save some $$$ on your food budget.
I hope I made sense to you ... sometimes I only seem to make sense to myself.

If I didn't quite answer your question PLEASE let me know and I will answer it as quickly as I can!!!
Take Care & Be Safe!
Frank
Disney DieHard