cut back vs lessen

cut back and lessen both are verbs.

Word	Noun	Adjective	Verb	Adverb
cut back	No	No	Yes	No
lessen	No	No	Yes	No

As verbs, lessen is a hypernym of cut back; that is, lessen is a word with a broader meaning than cut back:

Other hypernyms of cut back include decrease, minify.

cut back (verb)	lessen (verb)
place restrictions on	decrease in size, extent, or range
cut down on; make a reduction in	wear off or die down
cultivate, tend, and cut back the growth of	make become smaller
return in time