Though both wallets are totally safe and can only be accessed by the user, there are some differences that should be taken into consideration, when choosing the type of wallet.
The way your keys are stored;
With T-wallet, your passphrase is stored on Tokenomica’s servers, encrypted by your account password. If anyone gets your password, your account can be compromised.
With Waves Keeper, your keys are stored in a separate extension, which is protected by a separate password. These keys are a little bit harder to access from your computer.
Resetting the password;
If you reset the password you only lose access to your T-wallets. Waves Keeper wallets will still be available for use.
However, if you lose the password from Waves Keeper, you can lose your Keeper accounts too.
To prevent these situations always write down passphrases from your accounts. This way you will always be able to restore access to any account and will not worry about restoring any passwords.
Availability of the wallets;
T-wallets are only available on Tokenomica, while Waves Keeper can be used to interact with Waves Blockchain on other services.