orchestra vs symphony

orchestra and symphony both are nouns.

Word	Noun	Adjective	Verb	Adverb
orchestra	Yes	No	No	No
symphony	Yes	No	No	No

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

orchestra: a musical organization consisting of a group of instrumentalists including string players
symphony: a large orchestra; can perform symphonies

Other hyponyms of orchestra include chamber orchestra, string orchestra, philharmonic, symphony orchestra.

orchestra (noun)	symphony (noun)
seating on the main floor in a theater	a long and complex sonata for symphony orchestra
a musical organization consisting of a group of instrumentalists including string players	a large orchestra; can perform symphonies