tablet vs dosage

tablet and dosage both are nouns.

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

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

Other hypernyms of tablet include dose.

tablet (noun)	dosage (noun)
a dose of medicine in the form of a small pellet	a measured portion of medicine taken at any one time
a small flat compressed cake of some substance	the quantity of an active agent (substance or radiation) taken in or absorbed at any one time
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