Classic tabby is a pattern and can be found in lots of different breeds of cats (including your normal moggies).
The marble pattern in bengals started out as a variation of the classic tabby pattern. I.e the genes for the spotting reacted in an interesting and beautiful way with the classic tabby genes. People went oh wow that's a beautiful cat and lo and behold a new pattern was allowed in bengals.
Classic tabby is a pattern where instead of the stripes of a mackarel tabby you get thicker swirls running in a circular pattern on the cat's flank. It's really pretty. The pattern on the side is often called "a bulls eye".
In the marble bengals the pattern is more chaotic and the breeders are working hard at getting away from the bulls eye type pattern. The coat is usually clearer (not always though, there are for example some silver classic tabby American shorthairs that are really clear coated) it often has the bengal red rufous colouring in the coat and usually tricoloured. This is basically where the swirls have a dark outline and then a paler colour inside. Giving the cat three different colours in the coat. The background colour, the outline of the markings and the inside of the markings.
Of course marble bengals are also bengals so you'd expect to see puffy whisker pads, small ears, long body, thick tail and a demanding, active personality.
Photos! none of these are mine btw.
British shorthair brown classic tabby:
More british shorthairs
American shorthair, silver classic tabby
A simlar angle but this one is a marble bengal, the pattern has horizontal flow to it and the bulls eye pattern has been broken up. You can also see hints of a paler colour inside some of the pattern.
Another marble bengal with a very chaotic pattern and you can see the three colours easily
I'm not an expert though so please correct me if I've gone wrong but I figured it was worth it to get the conversation started.