If someone were to categorize handguns by type, I'd expect, "all-metal, double-stack, 9mm, frame-mounted thumb safety" could conceivably be a category into which "similar" guns might be ordered.
I really doubt anyone would make a category for, "Slide - with external rails - width of between 1.00"-1.1", frame to hold mags with greater than 13-round capacity, absence of mag disconnect, trigger guard large enough for NATO mittens, etc., etc." That category would contain one gun, and no other gun in the world could be considered similar to it.
The CZ is obviously no clone of the BHP, but as handguns go, they are much closer to "similar" than "totally different".
Is a large-frame Star .45 totally different from a 1911? I'd say no, for the same reasons, but you would say yes.
As the Russians say, "Everyone strokes differently".