The Main Characteristics of Felines
When I started art, I often failed to make canines and felines look different. Usually, cats would just have pointy ears and dogs would have floppy ears. However, if you have ever seen a cat or a dog, you know that they actually have a lot more differences than that, and even that dogs can have pointy ears and cats can have floppy ears, so that doesn't entirely work out.
Allow me to start with a cat, just a simple stereotypical shorthair:
image credits
You can already tell that this cat is not a dog, wolf, jackal or any other canid. So let's represent that in your art.
Let's start with the legs. Cat legs tend to have a large haunch, slanting downwards at the "knee" and then the leg from there goes forward. Think of it like there's two bends on the front, and three at the back.
Here, I sketched some cat legs. The top ones were done without reference, from my own memory. You can see my own advice being taken, however, when you look at the bottom sketches; you can see major differences. I included bones guides, which I don't often use myself, however if you need them please do use those.
Next, the tail. This one is fairly simple however a lot of people tend to do it wrong. Cat's tails are skinny and long. If they ever have a lot of fur on them, that fur will droop down rather than stick out in all directions because of gravity.
Fairly simple.
Now for the neck. Cats tend to be flat at the neck when standing, but when sitting their necks are a whole vertical drop.
Finally, the most important part, the face. All the details of a cat's face are completely different to that of a canid's. Cats have round, large eyes. Cats have short snouts. Cats have flat noses.
Now! Let's combine everything we've learned. I'll be using the cat image at the top as reference.
You can easily see the differences between the two!
Just remember, cats have slanted hind legs with large haunches. Cats have long and thin tails. Cats have large, round eyes. Cats have short snouts. Cats have flat noses.
Note for mods, all references I used were from the same stock source as linked on the first image, and all sketch references were done by me!