A crimp terminal has a seperation in the metal, and requires you to crimp the terminal closed around the cable.
The welding lug is just a solid piece of copper that accepts the wiring. It requires no crimping and has no way of securely fastening the wire inside of it. However, they tend to hold fairly well since the wire can go inside of it about 3-4 inches, and electrical tape will do the rest.
Welding lug FTW.