What does day is to night as night is to day? What kind of phrase is this?

what does day is to night as night is to day?? What kind of phrase is this ???

i used to do these when I was younger. at times they could be opposites like you have above or it could be (ie. cold is to ice and hot is to coffee)

Idiomatic expressions are words that when put together have a different meaning than they have standing on their own. Night is about half of a 24 hour period, as is day. 'Night and day' covers the entire 24 hours. Saying a person works nights (or days) means something different than saying someone works night and day for example.