situation vs impasse

situation and impasse both are nouns.

Word	Noun	Adjective	Verb	Adverb
situation	Yes	No	No	No
impasse	Yes	No	No	No

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

situation: a complex or critical or unusual difficulty
impasse: a situation in which no progress can be made or no advancement is possible

situation (noun)	impasse (noun)
a job in an organization	a street with only one way in or out
physical position in relation to the surroundings	a situation in which no progress can be made or no advancement is possible
the general state of things; the combination of circumstances at a given time
a condition or position in which you find yourself
a complex or critical or unusual difficulty