Schilke 44E4 vs Schilke 45B
The Schilke 45B has a wider cup diameter, the Schilke 44E4 features a deeper cup.
Cup Diameter
The Schilke 45B has a cup diameter of 24.30 mm / 0.9567 in compared to 24.28 mm / 0.9559 in on the Schilke 44E4 — a difference of 0.02 mm / 0.0008 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Schilke 44E4 has a very deep cup while the Schilke 45B has a medium cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
Throat diameters are essentially identical at 5.95 mm / 0.2343 in, so resistance feel will be comparable.
Which is better?
Neither mouthpiece clearly dominates the other — the right choice depends on your embouchure, playing style, and the sound you're after. Try both if possible.