Payer and receiver
=> Payer = the right to PAY fixed. Wins when rates rise. A call on the swap rate, which is also a put on bonds.
=> Receiver = the right to RECEIVE fixed. Wins when rates fall. A put on the swap rate, a call on bonds.

Same strike, at the money, both together = a straddle: a pure bet on the size of the move, not its direction.
Common trap: a payer is not a put. It only looks like one from the bond price side. Always reason in rates.