tablet vs iPad

tablet and iPad both are nouns.

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

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

tablet (noun)	iPad (noun)
a dose of medicine in the form of a small pellet	a table computer from Apple Inc
a small flat compressed cake of some substance
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