Syntactic categories
Syntactic categories are either phrasal categories, such as NP or VP, which can be decomposed into smaller syntactic categories or lexical categories, such as noun or verb, which cannot be further decomposed.In terms of phrase structure rules phrasal categories can occur to the left side of the arrow, while lexical categories cannot.
The lexical categories are traditionally called the parts of speech. They include nouns, verbs, adjectives etc.