Norell's is excellent stuff. As others have mentioned, it's a substantially thicker coating, but in my humble opinion is the tougher product if you're OK with the thickness factor. I wouldn't use it on tight tolerance or hand fitted parts--that's where Cerakote shines.
By way of example: Assuming all things equal in terms of proper surface prep and application, Norell's wins at abrasion resistance. I Cerakoted a Glock slide and an AR A2 receiver set in Norell's. The Cerakoted slide exhibited much quicker wear from the in and out of Safariland ALS holsters. The A2 receivers (a project to clone a "worn looking early M4) were manually "sanded" to imitate worn edges, and that abrasion took *work* to rub down into the aluminum.
If you suspect the part you're looking to refinish will have consistent scratching and abrasion applied to it, I think Norell's is the way to go if you want to prolong metal coverage. Either product will show wear in said scenario, but I think Norell's will maintain more metal coverage during the same period.