electronic computer vs computing device

electronic computer and computing device both are nouns.

Word	Noun	Adjective	Verb	Adverb
electronic computer	Yes	No	No	No
computing device	Yes	No	No	No

As nouns, electronic computer and computing device are synonyms defined as:

electronic computer and computing device: a machine for performing calculations automatically

Other synonyms of electronic computer include computer, computing machine, data processor, information processing system.

electronic computer (noun)	computing device (noun)
a machine for performing calculations automatically	a machine for performing calculations automatically