How shales, mudstone and siltstone are different

Mudstone and Shale. Mudstones and shales are made of silt- and clay-sized particles that are too small to see. The only difference between mudstone and shale is that mudstones break into blocky pieces whereas shales break into thin chips with roughly parallel tops and bottoms. ... Many shales are rich in fossils.

Ithink it’s a i’m not 100 percent sure though