observer vs looker

observer and looker both are nouns.

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

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

observer: a person who becomes aware (of things or events) through the senses
looker: a close observer; someone who looks at something (such as an exhibition of some kind)

observer (noun)	looker (noun)
a person who becomes aware (of things or events) through the senses	a very attractive or seductive looking woman
an expert who observes and comments on something	a close observer; someone who looks at something (such as an exhibition of some kind)