What Is the Difference between a Futures Contract and a Perpetual Swap?

The main difference is the expiration date. A traditional futures contract has a set expiry date, after which the contract is settled.

A perpetual swap, as its name suggests, has no expiry date. To manage the lack of settlement, perpetual swaps use a funding rate mechanism to keep the contract price in line with the spot price of the underlying asset, which futures contracts do not require.