harvestman vs daddy longlegs

harvestman and daddy longlegs both are nouns.

Word	Noun	Adjective	Verb	Adverb
harvestman	Yes	No	No	No
daddy longlegs	Yes	No	No	No

As nouns, harvestman and daddy longlegs are synonyms defined as:

harvestman and daddy longlegs: spiderlike arachnid with a small rounded body and very long thin legs

Other synonyms of harvestman include Phalangium opilio.

harvestman (noun)	daddy longlegs (noun)
spiderlike arachnid with a small rounded body and very long thin legs	long-legged slender flies that resemble large mosquitoes but do not bite
	spiderlike arachnid with a small rounded body and very long thin legs