The first is a common plec and the second a bristlenose.
Personally I would be bagging up the common plec and take it back to the shop and tell them you asked and payed for a bristlenose which it certainly isnt. They get HUGE and messy.
I bought 3 that were sposed to be BN but one died during an Ick treatment. It looked like the second one, so I think they were right and this guy just snuck into the wrong tank?