exercise vs tone up

exercise is a noun but tone up is not a noun.

Word	Noun	Adjective	Verb	Adverb
exercise	Yes	No	Yes	No
tone up	No	No	Yes	No

As verbs, tone up is a hyponym of exercise; that is, tone up is a word with a more specific, narrower meaning than exercise:

Other hyponyms of exercise include limber up, loosen up, warm up, train, tumble, strengthen, tone, press, weight-lift, weightlift.

exercise (noun)	tone up (noun)
the activity of exerting your muscles in various ways to keep fit
a task performed or problem solved in order to develop skill or understanding
systematic training by multiple repetitions
the act of using
an action, often used negatively and without consequences
(usually plural) a ceremony that involves processions and speeches

exercise (verb)	tone up (verb)
do physical exercise	give a healthy elasticity to
give a workout to
learn by repetition
put to use
carry out or practice; as of jobs and professions