G998U1 is a factory unlocked version of the S21 Ultra, it comes with all the antennas and doesn't include any carrier bloatware, as it's made to work with all carriers worldwide (depends on the bands the carrier uses tho) G998U is the version sold by different carriers such as T-Mobile, AT&T and Verizon and so on , it's locked to work specifically with aforementioned carriers unless to unlock the phone.
