Unlike a brass instrument, the saxophone is a wide conical tube with holes in the side. The concept of having what brass players call "back pressure" in a saxophone is unclear to me. When one blows a stream of air into a trumpet leadpipe one feels the air being held back or "resistance". This is its "back pressure" and is related to the taper and diameter of the bore. Blowing into the neck of a saxophone, with or without any pads closed produces no resistance at all by comparison.
On a saxophone, the "resistance" the player blows against is created by the slit between the mouthpiece and the tip of the reed as the reed "beats" against the mouthpiece opening and closing the pathway for the air. This resistance is determined by the geometry of the mouthpiece and the strength and cut of the reed as well as the player's embouchure. There is no "back pressure" inside the instrument that is holding the player's air back, it is meeting resistance at the entrance of the instrument.
There is however an effect in the saxophone that is called the "response" of the instrument. On a saxophone that is poorly designed and the harmonics are slightly out of tune, the coupling between the vibrations of the reed and the natural resonances inside the body of the instrument are not as efficient, producing an instrument that feels "stuffy" to the player. A "stuffy" instrument requires more energy input from the player to produce a sound than a "responsive" instrument to produce the identical sound.
We all have experienced that D is a "stuffy" note compared to the short tube notes on the saxophone and requires more air and breath support (pressurized air) to match the timbre of surrounding notes. This "stuffy" quality is not the result of the body tube pushing back against the air blown into the instrument as on a trumpet. Instead it is caused by the fact that D uses a longer tube that goes around a "U" bend in the body, and the fact that D is a poorly vented note. It is a poorly vented note because the tonehole that vents the D, the low C, is followed by a closed tonehole the low C#.
I think that this is more than just semantics because it involves the basic concepts and principals of how instruments work.