Yes, it's true that when it comes to actual policy, there's virtually no daylight between Marco Rubio and Mitt Romney. Nonetheless, on Tuesday night we learned about a big difference between the two men. A very, very big difference.
Compare the size of Romney's bottle in this photo:
Now, I'll admit, I've got no idea why Rubio decided to go small. Perhaps it's because he knows that a higher plastic-to-water ratio is worse for the environment and he wanted to bolster his credentials as an Earth-hating man of God unconcerned about trivialities like climate change.
Or maybe he just wanted a small container because he thought if he had a small enough bottle, he could sneak a sip without anybody noticing. (That would explain why his eyes remained locked on the camera as he guzzled.) Really, your guess is as good as mine. The only thing I'm sure about is that I've never seen anything like it before.