To address the primary question, no, they appear to not be different anD really both are variable in power and stats. However, I would caution this statement by asking what team you are on? Yellow team may have more pronounced hatching powers vs blue has more powerful evolutions vs red might find more powerful in the wild or gain cp faster when leveling up. The game simply needs to be played more to find out these nuances.
What I really wanted to mention though was in regards to the starter pokemon being "useless":
I've been holding onto my starter squirtle in the off chance that there is secret coding that will make it super powerful if I level it up long term in the future. If you know about the evee evolution choice trick then you know that it's a possibility they would do something like that.... and if you transferred yours to the professor then you'll be SOL...check out the evee thing on other forums and you'll get why I'm saying this.
It may not be relevant now, it may never be, but I have a feeling, as a long term ingress player, this game will only get more complex alon with the programming anD secret tricks. There WILL be a reason to have kept it...eventually. which will lead more people to create a second or third account to get a starter starter again most likely. This guy who commented there wasn't any reason is just upset now bc he probably transferred his already and wasn't thinking about the long term :(
I'm a level 22 who refuses to pay to play. I'm all about the smart playing and live in a dense urban environment. I think your first starter could be worth holding onto...just in case. That's just my best advice.
BTW I caught a 488 squirtle yesterday and my highest wild catch was a 1270 arcanine. There are wild evolved charizards around here somewhere too. And my buddy caught a Blastoise. That being said...keep your first! The data is in the system, it will know that was your first...