Different result when call assembly add in bytes and bytes32.

assemblyAdd.sol

pragma solidity 0.5.1;


contract ADD {
    event Add( uint256 indexed num );
    
    function Bytes(bytes memory _t) public {
        uint256 t;
        assembly {
            t := add(_t, 0)
        }
        emit Add(t);
    }
    
    function Bytes32(bytes32 _t) public {
        uint256 t;
        assembly {
            t := add(_t, 0)
        }
        emit Add(t);
    }
}