send-off vs bon voyage

send-off and bon voyage both are nouns.

Word	Noun	Adjective	Verb	Adverb
send-off	Yes	No	No	No
bon voyage	Yes	No	No	No

As nouns, send-off and bon voyage are synonyms defined as:

send-off and bon voyage: an organized expression of goodwill at the start of a trip or new venture

send-off (noun)	bon voyage (noun)
an organized expression of goodwill at the start of a trip or new venture	an organized expression of goodwill at the start of a trip or new venture
a start given to contestants