pathogen vs infective agent

pathogen and infective agent both are nouns.

Word	Noun	Adjective	Verb	Adverb
pathogen	Yes	No	No	No
infective agent	Yes	No	No	No

As nouns, infective agent is a hypernym of pathogen; that is, infective agent is a word with a broader meaning than pathogen:

pathogen: any disease-producing agent (especially a virus or bacterium or other microorganism)
infective agent: an agent capable of producing infection

Other hypernyms of pathogen include micro-organism, microorganism, infectious agent.

pathogen (noun)	infective agent (noun)
any disease-producing agent (especially a virus or bacterium or other microorganism)	an agent capable of producing infection