notice vs observe

notice is a noun but observe is not a noun.

Word	Noun	Adjective	Verb	Adverb
notice	Yes	No	Yes	No
observe	No	No	Yes	No

As verbs, observe is a hypernym of notice; that is, observe is a word with a broader meaning than notice:

Other hypernyms of notice include mention, note, remark.

As verbs, notice and observe are synonyms defined as:

notice and observe: discover or determine the existence, presence, or fact of by perception with the eyes

Other synonyms of notice include detect, discover, find.

notice (noun)	observe (noun)
the act of noticing or paying attention
polite or favorable attention
a sign posted in a public place as an advertisement
an announcement containing information about an event
a request for payment
advance notification (usually written) of the intention to withdraw from an arrangement of contract
a short critical review

notice (verb)	observe (verb)
make or write a comment on	stick to correctly or closely
express recognition of the presence or existence of, or acquaintance with	make mention of
notice or perceive	watch attentively
discover or determine the existence, presence, or fact of by perception with the eyes	observe with care or pay close attention to
	discover or determine the existence, presence, or fact of by perception with the eyes
	follow with the eyes or the mind
	show respect towards
	behave as expected during of holidays or rites
	conform one's action or practice to