There are some sealants that provide excellent UV protection and long durability, some provide excellent UV protection (while they last) and short durability, some provide little UV protection and long durability, and so-on and so-on. The same can be said for specific waxes as well...
Ultimately, it comes down to the individual product... More then what the main protective ingredient is. Wax and sealant manufacturers have a vested interest in protection your finish because it keeps them in business.
In general, I would prefer a paint sealant for protection, because, in general, they last longer then most carnauba waxes and withstand heat better. If you want a best of both worlds approach, apply a paint sealant first then top that with a carnauba wax.