There used to be a general impression that Flying Js were generally bigger (and better?) than Pilots, but there are so many counter-examples (both big Pilots and small Flying Js) that I think the distinction is irrelevant. Also, exits with two Pilots aren't unheard of. Examples: Exit 6 on I-65 in Kentucky, Exit 28 on I-71 in Kentucky, and Exit 167 on I-94 in Michigan.
I'm wondering if TA/Petro will do the same thing. Petro's logo is so boring and tired, it looks like it's just waiting to fade away. However, in my experience, I actually have noticed Petros to be generally bigger than TAs, and the distinction of having an Iron Skillet at Petro and a Country Pride at TA is fairly common, but again, there are exceptions where they have different restaurants. (As a side note, breakfast buffet at Iron Skillet is possibly my favorite dining experience ever.) I was about to mention the Petro at Exit 2 on I-10 in Texas having a tiny store with only a Subway, and having to walk across the street to get from the truck parking lot, but I just looked it up, and they've re-branded it as a TA Express, so they actually are making an effort at consistency between brand distinctions.
Edit: I meant I-10 in Texas, not New Mexico. Damn brain farts!