pruning vs trimming

pruning and trimming both are nouns.

Word	Noun	Adjective	Verb	Adverb
pruning	Yes	No	No	No
trimming	Yes	No	No	No

As nouns, trimming is a hypernym of pruning; that is, trimming is a word with a broader meaning than pruning:

Other hypernyms of pruning include clipping, trim.

pruning (noun)	trimming (noun)
the act of trimming a plant	the act of adding decoration
something that has been pruned off of a plant	cutting down to the desired size or shape
	a decoration or adornment typically on the edge of a garment