Brantly Millegan (Director of Operations at ENS) followed up via a post on Twitter.
.ETH names are ENS-native, which means ownership is purely whoever owns it on Ethereum. .XYZ names (and all names imported from DNS) follow the DNS side. This means DNS names imported into ENS have a different ownership/security model than .ETH names
ENS names = .ETH names + DNS names imported into ENS DNS names imported into ENS ultimately have the same security as normal DNS names (since the ENS side follows the ownership on the DNS side). .ETH names are as secure as your Ethereum private key and can be traded like NFTs.
Lastly, both domain types are supported in place of a wallet address when sending/receiving crypto in a supported wallet.