keyboard shelf vs keyboard tray

keyboard shelf and keyboard tray both are nouns.

Word	Noun	Adjective	Verb	Adverb
keyboard shelf	Yes	No	No	No
keyboard tray	Yes	No	No	No

As nouns, keyboard shelf and keyboard tray are synonyms defined as:

keyboard shelf and keyboard tray: a sliding tray that is a part of a computer desk, used to hold a keyboard.

keyboard shelf (noun)	keyboard tray (noun)
a sliding tray that is a part of a computer desk, used to hold a keyboard.	a sliding tray that is a part of a computer desk, used to hold a keyboard.