1. Unlimited limitations, you can just add on the APs as much as you like but I don't think that the same could happen with Unleashed. 2. Analytics and reports are something unique to Cloud. 3.Last but not Least Price, you have to pay subscription per year but not with Unleashed.
But, that cannot stop you to switch you to Cloud if you desire to, because I heard they are bringing AI if it is then they may add it to cloud and there is a separate team that is going to handle after sales cases that comes as an added advantage.
It depends on how you want it, everything is same on the background the same vSZ is running on Kubernets (Cloud Tech), but has different GUI and is made available on the platter.
This is just small gist if you want technical details.