which of these operating systems is better in terms of hidding the ip address and not leaking the ip address whonix or tails ???
and in whonix is there a kill swich to delete or encrypt all data like in tails you just unplug the flash drive ???
Apples and oranges - but all of this Whonix talk doesn't matter if you run Windows at the Host OS, for an example.
Same thing - you encrypt your Whonix with the Host OS. You CAN encrypt the workstation virtual disk file on VirtualBox and KVM technically also.
Same thing - you encrypt your Whonix with the Host OS. You CAN encrypt the workstation virtual disk file on VirtualBox and KVM technically also.
Depending on if you want some level of persistence running Whonix on BARE METAL is your best option. Tails is great if you want to have a portable solution for accessing TOR but if security is your main concern use WHONIX. As MrBacon said, the OS will automatically encrypt itself so that's not a concern.