Sounds like standard 16/4 wire they use for all new home pre-wire. By convention, yes Red/Black would be one pair and Green/White would be another, but it does not matter! It's wire.
As long as you are consistent in your hookup it doesn't matter which wires you use for which terminals. If you use the red wire for the positive terminal on the speaker make sure you connect the other end of the red wire to the positive terminal on the receiver. Likewise, black for negative.
For the other green/white pair, pick a convention and go with it. If you want to follow convention so people (like yourself!) can tell at a glance what is what then use the green wire for the positive and the white wire for the negative. On the receiver side that would mean connecting the green to the red terminal (it is the positive) and the white to the black terminal (the negative).