He's also Sixshot's son. What this even friggin' means has never been explored by Transformers fiction of any kind, but that familiar relation has been stated. It's canon, somehow. He's Sixshot's kid who's trying to make up for all the evil his daddy did. Does. Whatever. I mean, we have Transformers siblings of various kinds, Transformers cousins, Transformers spouses, but we have no idea what being a Transformers dad means outside of the job title existing. Could it be merely adoptive and not biological? Who knows!
The original Quickswitch had a few different modes than his dad. He could become a boat, a drilltank, and a different kind of four-legged animal other than a wolf. I want to say a puma? Regardless, this new Quickswitch is just Sixshot again in teal and red, so he doesn't get any of those unique modes.
If you have to choose between only Sixshot or Quickswitch, I'd go Quickswitch. Teal and red is just neat, plus he comes in a box set with Nautica, so.