The same pair can have several pools, each charging a different fee on every swap: commonly 0.01%, 0.05%, 0.3% or 1%.
Each tier is a separate pool with its own liquidity and its own price step — the smallest price gap a range edge can sit on.
A higher fee is not more income by itself: it also depends on how much trading that pool attracts.
Swappers go where the price is best after the fee, so the busiest tier of a pair is often one with a lower fee.
Liquidity follows fees in turn, and a tier with little of it gives each deposit a larger share of what it charges.
The pool pages here list every tier of a pair beside the one being read, with how deep each is.