It's funny that king and queen are the only two commanders in the story so far that are always paired up as a duo on fights and etc but ppl think king is like 3 tiers above queen lol.
It's cause Zolo fans can't read. King and Queen have the lowest difference in their bounties between any 1st and 2nd commander (both in 1.3b range similar to Kaku and Jabra's doriki's), they have a 1cm difference in their heights (similar to Zoro and Sanji, Shanks and Mihawk), they're constantly arguing like other rivals (only commanders who have this dynamic similar to Broggy and Dory, Zoro and Sanji, Kaku and Jabra) and they're of course like you said always portrayed together in contrast with other commanders.
Oda couldn't make the fact that they're similar in strength anymore clearer but Zolo fans gotta wank Zolo.