Well god damn it, you're right.

Even disregarding the nutritional facts, I made such a big deal out of the 1 Liters not having those damn grippy bits and didn't even look closely enough at the bottle on the right to realize that it didn't have a damn grippy bit. It's smooth-waisted.

I'd thank you for pointing out my mistake but I'm too busy eating my own words and being salty about it.

Honestly, as someone who used to drink a minimum of two 20-oz bottles of Dew a day... I wouldn't really recommend it.

With all due respect, you are 100% incorrect.

The only Mountain Dew bottles above the 20 oz are the gigantic Liter sizes, and those are too chunky to fit in even the more generously-sized car cupholder. The Liter sizes are also shaped very differently (they don't have that narrower grip part), so they're pretty visually distinctive. So the taller one (on the right) can't be anything other than the 20 oz.

Whereas the 13? 16? (can't remember which) sized bottle is narrower overall, shorter, and has a noticeably smaller cap, so the one on the left is 100% not the 20 oz. And the only bottles smaller than the 13? oz are the glass bottles and the tiny 8 oz. It can't be an 8 oz because the 8 oz bottles don't have that narrow grip bit at all and tend to also have black caps, not green.

ETA: I'll be damned, I was the one who was 100% incorrect. The one on the right is a 1-Liter, and the one on the left is the 20 oz. This is why you shouldn't get addicted to Mountain Dew, kids: it rots your brain cells and isn't even good for being an accurate know-it-all regarding Mountain Dew bottles on the Internet.

I used to be a Mountain Dew addict. I am not proud of this, but I can say with absolute certainty that the smaller/skinnier bottles (>16 oz) are made with a slightly lighter green plastic, and the bigger ones (<20 oz) are made with a slightly darker green plastic. The bigger bottles are also made of a thicker plastic, so that could also effect the color.

I guarantee you, OP, if you pour out the actual liquid of both bottles into clear glasses, they're the exact same shade of almost-but-not-quite-piss-yellow. It's the bottles themselves that are different.