There're two possible locations for xdb_wallet.
Single-instance Databases
The root entry of xdb_wallet is $ORACLE_BASE for single-instance databases.
$ORACLE_BASE/admin/$ORACLE_SID/xdb_wallet/
RAC Databases
The root entry of xdb_wallet is $ORACLE_HOME for RAC databases.
$ORACLE_HOME/admin/<DB_UNIQUE_NAME>/xdb_wallet/
That's the difference.
Putting wallets including Transparent Data Encryption (TDE) keys in $ORACLE_HOME has some advantages, one of which is that, when we backup Oracle home, wallets are also included.