stewing vs simmering

stewing and simmering both are nouns.

Word	Noun	Adjective	Verb	Adverb
stewing	Yes	No	No	No
simmering	Yes	No	No	No

As nouns, stewing and simmering are synonyms defined as:

stewing and simmering: cooking in a liquid that has been brought to a boil

Other synonyms of stewing include boiling.

stewing (noun)	simmering (noun)
cooking in a liquid that has been brought to a boil	cooking in a liquid that has been brought to a boil
an extreme state of worry and agitation