upgrade vs gentle

upgrade is a noun but gentle is not a noun.

Word	Noun	Adjective	Verb	Adverb
upgrade	Yes	No	Yes	No
gentle	No	Yes	Yes	No

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

Other hyponyms of upgrade include tenure, bring up, spot promote, ennoble, entitle, favor, favour, prefer, brevet.

upgrade (noun)	gentle (noun)
the act of improving something (especially machinery) by raising it to a higher grade (as by adding or replacing components)
hardware that provides better performance than an earlier version did
the property possessed by a slope or surface that rises
a reservation that is improved
software that provides better performance than an earlier version did
an upward slope or grade (as in a road)

upgrade (adjective)	gentle (adjective)
	marked by moderate steepness
	having little impact
	soft and mild; not harsh or stern or severe
	belonging to or characteristic of the nobility or aristocracy
	quiet and soothing
	easily handled or managed
	having or showing a kindly or tender nature

upgrade (verb)	gentle (verb)
to improve what was old or outdated	stroke soothingly
give better travel conditions to	cause to be more favorably inclined; gain the good will of
get better travel conditions	give a title to someone; make someone a member of the nobility
rate higher; raise in value or esteem
give a promotion to or assign to a higher position