The difference between Lexical category and Part of speech

When used as nouns, lexical category means a linguistic category of words (or more precisely lexical items), generally defined by the syntactic or morphological behaviour of the lexical item in question, such as noun or verb, whereas part of speech means a linguistic category of words sharing syntactic or morphological behaviour and semantic properties, such as noun or verb.

check bellow for the other definitions of Lexical category and Part of speech