tablet vs computer

tablet and computer both are nouns.

Word	Noun	Adjective	Verb	Adverb
tablet	Yes	No	No	No
computer	Yes	No	No	No

As nouns, computer is a hypernym of tablet; that is, computer is a word with a broader meaning than tablet:

tablet (noun)	computer (noun)
a dose of medicine in the form of a small pellet	a machine for performing calculations automatically
a small flat compressed cake of some substance	an expert at calculation (or at operating calculating machines)
a slab of stone or wood suitable for bearing an inscription
a portable computer with a touchscreen
a number of sheets of paper fastened together along one edge