speedskater vs speed skater

speedskater and speed skater both are nouns.

Word	Noun	Adjective	Verb	Adverb
speedskater	Yes	No	No	No
speed skater	Yes	No	No	No

As nouns, speedskater and speed skater are synonyms defined as:

speedskater and speed skater: an ice-skater who races competitively; usually around an oval course

speedskater (noun)	speed skater (noun)
an ice-skater who races competitively; usually around an oval course	an ice-skater who races competitively; usually around an oval course