trouble vs happening

trouble and happening both are nouns.

Word	Noun	Adjective	Verb	Adverb
trouble	Yes	No	Yes	No
happening	Yes	No	No	No

As nouns, happening is a hypernym of trouble; that is, happening is a word with a broader meaning than trouble:

Other hypernyms of trouble include natural event, occurrence, occurrent.

trouble (noun)	happening (noun)
an effort that is inconvenient	an event that happens
a source of difficulty
an event causing distress or pain
an angry disturbance
a strong feeling of anxiety
an unwanted pregnancy

trouble (verb)	happening (verb)
cause bodily suffering to and make sick or indisposed
disturb in mind or make uneasy or cause to be worried or alarmed
move deeply
to cause inconvenience or discomfort to
take the trouble to do something; concern oneself