washer vs window washer

washer and window washer both are nouns.

Word	Noun	Adjective	Verb	Adverb
washer	Yes	No	No	No
window washer	Yes	No	No	No

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

Other hyponyms of washer include laundryman, washerman, laundress, laundrywoman, washerwoman, washwoman, washman.

washer (noun)	window washer (noun)
a home appliance for washing clothes and linens automatically	someone who washes windows
seal consisting of a flat disk placed to prevent leakage
someone who washes things for a living