It hits slightly different though.

For example graceful degradation could be considered when a device can have different components fail but the rest still work.

Progressive enhancement can be considered to be a device with basic functionality with optional add-ons.

It's basically about the base getting less functional, versus the baseline being upgraded. From a certain point of view they are the same thing but realistically they're not.

If I have a device with an optional add-on and I don't actually have that add-on installed, I wouldn't say the device is "degraded", even though technologically it probably doesn't make much difference.