situation vs crowding

situation and crowding both are nouns.

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

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

situation: the general state of things; the combination of circumstances at a given time
crowding: a situation in which people or things are crowded together

situation (noun)	crowding (noun)
a job in an organization	a situation in which people or things are crowded together
physical position in relation to the surroundings
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