Lightning support is one big difference:

this is the place to start learning about the platform: https://learn.robosats.com/

It is, but with some bumps. I managed to do that, but first I sent some sats to my phoenix from elsewhere and after some time the transaction from robosats went through. But I paid a lot for the channel opening. I bought too much at a time, I think. For more than 100$ I would next time try onchain. Maybe I'm missing something though, my LN understanding is poor still. I guess I'll go ask ChatGPT ;)