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

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

A perpetual swap (or perpetual futures contract) has no expiry date and can be held indefinitely. To keep its price aligned with the spot market, the perpetual swap uses a funding rate mechanism, which is the other key difference not present in traditional futures.