This is very hotel-dependent as there isn't a strict benchmark. One hotel may use "superior" where another might use "deluxe" for the same definition of features.
To some extent it also depends what you consider "better", as the rooms might be identical with the only difference being lower vs higher floors, or garden vs street view. When you're searching Expedia for your accommodation, take a moment to scroll through each room's description and pictures to compare and find the best option for you. You can also read guest reviews for room recommendations.