learner vs nerd

learner and nerd both are nouns.

Word	Noun	Adjective	Verb	Adverb
learner	Yes	No	No	No
nerd	Yes	No	No	No

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

learner: someone (especially a child) who learns (as from a teacher) or takes up knowledge or beliefs
nerd: an insignificant student who is ridiculed as being affected or boringly studious

Other hyponyms of learner include memoriser, memorizer, quick study, sponge, dweeb, grind, swot, wonk, tutee.

learner (noun)	nerd (noun)
someone (especially a child) who learns (as from a teacher) or takes up knowledge or beliefs	an insignificant student who is ridiculed as being affected or boringly studious
works for an expert to learn a trade	an intelligent but single-minded expert in a particular technical field or profession