I haven't tried xpra specifically, but from your description it reminds me of regular X server running on either windows or mac is (xming and xquartz respectively).
Nope, completely different. Xpra is resistant to network failures, while X server requires a stable network connection to keep the apps running. Xpra is also completely agnostic to the applications GUI: it just streams video and input events.
Rough X vs Xpra sketch:
| |
display <-> X server | <----X proto-----> | app
| |
| |
display <-> Xpra client | <---h264/input---> | Xpra server <-X proto-> app
| |
|~~~~~~network~~~~~~~|
