talk vs prophesy

talk is a noun but prophesy is not a noun.

Word	Noun	Adjective	Verb	Adverb
talk	Yes	No	Yes	No
prophesy	No	No	Yes	No

As verbs, prophesy is a hyponym of talk; that is, prophesy is a word with a more specific, narrower meaning than talk:

Other hyponyms of talk include preach.

talk (noun)	prophesy (noun)
the act of giving a talk to an audience
an exchange of ideas via conversation
idle gossip or rumor
a speech that is open to the public
discussion; (`talk about' is a less formal alternative for `discussion of')

talk (verb)	prophesy (verb)
express in speech	predict or reveal through, or as if through, divine inspiration
exchange thoughts; talk with	deliver a sermon
reveal information
use language
deliver a lecture or talk
divulge confidential information or secrets