Actually, they are the same car under the skin. Different styling yes. But same 3.6 Liter engine. Same transmission, everything under the restyled body is the same. Styling doesn't break down, engines, transmissions, ac compressors etc, the things they have in common do.
Actually, no, they're not the same...at all. The Dodge Grand Caravan is a hold over from the previous generation, dating back many years. The Chrysler Pacifica is an entirely new platform which it does not share with the Grand Caravan. The only major thing they have in common is the engine. Different transmission, different unibody, interior, electrical etc... The old Chrysler Town and Country was a clone of the Grand Caravan, but the Dodge and Chrysler today are vastly different and share very, very little.
OP, if you want stow n go, pretty sure the only ones offering it are Dodge and Chrysler. You'd be wise to have concerns about them otherwise. As I mentioned above, the Grand Caravan is a very dated design and in the absolute back of the pack. Unless you're just looking for the very cheapest new minivan you can get, avoid it. The Pacifica is much better, but still a mid-pack at best minivan...plus you'll get all the reliability that Fiat and Chrysler have to offer...which is to say not much.
We've had minivans for 11 years now, which for a car obsessed guy like me probably seems odd. However, I absolutely love them. We've had Kia Sedonas, as I think they're the best bargain out there. We have the older generation, but the newest one is a darn good van. I believe that generation came out in '15 or so. You can find a lightly used 2 or 3 year old one for a song, I'd definitely look at them. They're quality is outstanding. They're not quite up to the full "refinement" of the class leaders, but for the money you pay, they're hard to beat.
The top of the class in minivans is still the Honda Odyssey. It's the best minivan money can buy, period. But yes, it'll cost you more. The Sienna is probably a close second, but again, it costs more. Honda and Toyota quality is the best in the entire automotive industry, bar none.
As a wild card, check out the Ford Transit Connect. Pretty neat van, but not the absolute best.
I'd suggest thinking long and hard how much you really need stow n go. In the 11 years we've had our vans, I can count on one hand the number of times I wish we had it. Chrysler does offer that, but you'll suffer everywhere else.