noticer vs observer

noticer and observer both are nouns.

Word	Noun	Adjective	Verb	Adverb
noticer	Yes	No	No	No
observer	Yes	No	No	No

As nouns, observer is a hypernym of noticer; that is, observer is a word with a broader meaning than noticer:

noticer: someone who takes notice
observer: a person who becomes aware (of things or events) through the senses

Other hypernyms of noticer include beholder, perceiver, percipient.

noticer (noun)	observer (noun)
someone who gives formal notice	a person who becomes aware (of things or events) through the senses
someone who takes notice	an expert who observes and comments on something