The "body"/tube on the CZ-75B (.40) mag and the CZ-40B mag are identical, but the baseplates are different. The 40B uses a thicker (on the front) "decorative" baseplate -- and its mags won't fit in the standard 75B. The thicker baseplate keeps it from locking in place. But, the 75B mag (with a thinner bottom) will fit the 40B -- with the gap mentioned.
Just be careful that you're not getting mags for the Tactical Sport. Sounds as though the 14 rounders should work fine(since they're cited as working with the 40B, too). I'd be wary of the 16-rounders unless they'll pay return postage if they don't fit.
Note: The 40P has a compact frame (based on the 9mm P-01) adapted to work with the 40B slide. The P-01 gun was designed to use a [compact] smaller mag; they modified the 40P to be sold with a with a full-size mag and that full-size mag uses a filler that works as a grip extension. Get those "fillers" from CZ and you can use any CZ mag for the full-size guns with the 40P. The tubes are the same.