amount vs subtotal

amount and subtotal both are nouns.

Word	Noun	Adjective	Verb	Adverb
amount	Yes	No	Yes	No
subtotal	Yes	No	No	No

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

Other hyponyms of amount include grand total.

amount (noun)	subtotal (noun)
how much there is or how many there are of something that you can quantify	the sum of part of a group of numbers
the relative magnitude of something with reference to a criterion
a quantity obtained by the addition of a group of numbers
a quantity of money

amount (verb)	subtotal (verb)
to measure up to in kind or quality
add up in number or quantity
be tantamount or equivalent to