theme vs topic

theme and topic both are nouns.

Word	Noun	Adjective	Verb	Adverb
theme	Yes	No	Yes	No
topic	Yes	No	No	No

As nouns, theme and topic are synonyms defined as:

Other synonyms of theme include subject.

theme (noun)	topic (noun)
a unifying idea that is a recurrent element in literary or artistic work	some situation or event that is thought about
the subject matter of a conversation or discussion	the subject matter of a conversation or discussion
an essay (especially one written as an assignment)
(music) melodic subject of a musical composition
(linguistics) the form of a word after all affixes are removed

theme (verb)	topic (verb)
provide with a particular theme or motive