Two major differences in the morphology of spermatids and spermatozoa

The spermatid is a circular cell containing a nucleus with DNA not too compacted, Golgi apparatus, centriole mitochondria. When spermatid go through spermiogenesis all these components will form the spermatozoon.

Spermatozoa have a tail (formed by one centriole), DNA more condensed and an acrosomal cap (formed by the Golgi apparatus).