Since they are both 'non-limited' packs, they both faced degradation. I would assume that they've lost about 5% in the first 2 years and that would mean you're really talking about an 81kwh and a 57kwh battery here. Mileage difference is not substantial so really, the only thing that you need to look at is the VIN delta and whether features (AP, etc), and / or design differences are present. I've driven many cars from 2013 and 2014 and they are all very different as Tesla made a lot of design changes back then (prime example is a fully modified sunroof design). Also, I'd definitely choose 19's over 21's as it's just quieter, more economical, cheaper to replace / repair. IF that choice is present here. Link to the cars maybe?