Sealing and waxing are both for protection of the paint. They differ only in the stuff used and the protection they offer. Sealants are mostly synthetic while waxes are based mostly on oils. The main difference would be durability and subjective gloss. If you wax often, then you may not require a sealant process. But even if you do wax weekly or whatever, some people prefer the look of sealants over waxes.

One addition is that sealants usally attract less dust than waxes.

Since sealants and waxes are both paint protecting products, they are essentially the same with the exceptions mentioned above. But both require periodic reapplication but sealants require less frequent applications.