Yes they are definitely different.
See, d’Anvers have a bull neck, extreme tail angle, very short back, upright posture.
View attachment 2167820 Not my pic
Here is the difference between Watermaels and d’Anvers.
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The Watermael has a trilobed beard and tighter feathering along with a more gradual type.
View attachment 2167833 Not my pic
A d’Uccle kinda looks more like it’s crouching and leaning forward instead of upright. A d’Uccle has some Asiatic blood which brought in the feathered legs to the Belgian bantams. It has a more flat back than the other two which basically have v or u shaped backs (no their skeletons aren’t shaped like that, but their feathers make it look that way.)
There are also tailless versions of these breeds, these being true varieties of the breeds, respectively d’Grubbe, d’Everburg, and de Boitsfoot.