peak vs pinnacle

peak and pinnacle both are nouns.

Word	Noun	Adjective	Verb	Adverb
peak	Yes	No	Yes	No
pinnacle	Yes	No	Yes	No

As nouns, pinnacle is a hyponym of peak; that is, pinnacle is a word with a more specific, narrower meaning than peak:

Other hyponyms of peak include brow, hilltop, mountain peak.

As nouns, peak and pinnacle are synonyms defined as:

peak and pinnacle: the highest level or degree attainable; the highest stage of development

Other synonyms of peak include acme, elevation, height, meridian, summit, superlative, tiptop, top.

peak (noun)	pinnacle (noun)
a brim that projects to the front to shade the eyes	(architecture) a slender upright spire at the top of a buttress or tower
the top or extreme point of something (usually a mountain or hill)	a lofty peak
the highest point (of something)	the highest level or degree attainable; the highest stage of development
the most extreme possible amount or value
a V shape
the highest level or degree attainable; the highest stage of development
the period of greatest prosperity or productivity

peak (verb)	pinnacle (verb)
to reach the highest point; attain maximum intensity, activity	raise on or as if on a pinnacle
	surmount with a pinnacle