erect vs upright

erect is not a noun while upright is a noun.

Word	Noun	Adjective	Verb	Adverb
erect	No	Yes	Yes	No
upright	Yes	Yes	No	No

As adjectives, erect and upright are synonyms defined as:

Other synonyms of erect include vertical.

erect (noun)	upright (noun)
	a piano with a vertical sounding board
	a vertical structural member as a post or stake

erect (adjective)	upright (adjective)
upright in position or posture	upright in position or posture
of sexual organs; stiff and rigid	of moral excellence
	in a vertical position; not sloping

erect (verb)	upright (verb)
construct, build, or erect
cause to rise up