Hi, this is area-adjacent to my doctorate, and will try to simplify as best I can

The actual imprint, shape, and color are specifically used to distinguish manufactured products, and have no bearing on how the drug works.

Now, as to size and coatings, thats a little more complex.

Multiple drug delivery schema exist, such as long acting / intermediate acting / short acting, delayed release, sustained release, abuse-deterrent, and so on. This is in addition to films or coatings designed either to protect you or protect the drug as it travels from your mouth to the stomach to the rest of the digestive tract.

Some drugs will become inactivated due to strong stomach acids, and thus are either coated or buffered to survive past that step.

Some drugs are specifically formulated to become active either in the acidic stomach or relatively basic small intestine, so the reverse to the above situation is also possible.

Other drugs do not become active until they are absorbed by the body and chemically acted upon by the liver.

Some drugs are so poorly absorbed from the digestive tract that they require such large doses just to achieve their desired effect, and you can recover upwards of the majority 70-80% in your poop, nevermind the specific anti abuse or long acting delivery vehicle showing up just like kernels of corn in the toilet bowl.

Size is a mixed bag, as the actual manufacturing process takes these drugs, often in powder form, extremely precisely and with likewise extreme accuracy adds it to fillers, anti caking agents, dry lubricants, and so on in order to create said tablet via industrial machinery. This applies to the vast majority of tablets and capsules.

Some of the long acting or sustained release formulations specifically dissolve slowly (or not at all!) and there is very complex math involved to make sure those forms release the drug in the right amount over the right amount of time