what is the different between wallet.dat and virgin_wallet.dat and full_wallet.dat ?
Bitcoin Core uses wallet.dat by default, the other wallets are probably renamed (by the user). I've collected many different filenames over the years too.
how do you know the address of that wallet without downloading all bitcoin core ?
It's easiest to download Bitcoin Core, but you don't need to download the 300+ GB blockchain.
After loading the wallet, click Help > Debug window > Console > Enter "listaddressgroupings".
is there away to know what kind of wallet.dat is becouse i see etherum wallet and peercoin wallet
Wallet.dat belongs to Bitcoin Core, but it can be an altcoin (like Peercoin).
bitcoin-wallet-backup-2015-10-10
This is created by
Bitcoin Wallet on Android. Use this app to restore your backup.
Darkcoin-wallet-keys-2014-07-22
Dash-wallet-backup-2015-08-23
These sounds like the above, but for an altcoin again.
walletFTC ?
Feathercoin.