circumstance vs environment

circumstance and environment both are nouns.

Word	Noun	Adjective	Verb	Adverb
circumstance	Yes	No	No	No
environment	Yes	No	No	No

As nouns, environment is a hypernym of circumstance; that is, environment is a word with a broader meaning than circumstance:

circumstance: the set of facts or circumstances that surround a situation or event
environment: the totality of surrounding conditions

circumstance (noun)	environment (noun)
information that should be kept in mind when making a decision	the area in which something exists or lives
formal ceremony about important occasions	the totality of surrounding conditions
a condition that accompanies or influences some event or activity
the set of facts or circumstances that surround a situation or event