OWL Ontologies consists of
Properties which are compariable to Classes, Objects and Properties in RDFS (RDF Schema). However they are not the same. For instance, simple Classes in OWL are much more complicated and exhibit more Semantic Expressivity compared to those Classes in RDFS, because simply Classes in OWL can be restricted in various ways, whereas RDF Classes can not.
Classes: comparable with Classes in RDFS
Individuals: comparable with Objects in RDFS
Properties: comparable with Properties in RDFS