So, in my Great Forms novel (series) I have three creatures, The Ice Drake, the Silver Wyrm and the Black Dragon, who in theory could be very similar looking. After all they're all dragonic 'types'. However I didn't just want them to be the same 'dragon' form with different colors or abilities. So these sketches are what I came up with:

The Ice Drake I imagined as a four limb creature, his wings and hands being the same thing. His face is square and blunt and he's got a nice series of thick wide spikes on his back for armor. Living up in the north where he does he has to deal with Ice Giants which are like polar bears on steroids.

(I haven't get around to coloring this one yet, silver is HARD.)
The Wyrm I went with something rounder. He's not a fighter and he doesn't have to deal with much in the way of dangers. He's a scholar. The Wyrm is also comfortable in the rivers and waterways so he needed a very sleek design. His wings can fold flat against him when he's in the water or act like fins. He has a hording tendency but it tends more to useful collections than straight treasures. Also he's able to part with his treasures if he thinks it will do good.

This guy is our 'traditional' looking dragon. He's very dark colored and doesn't have any shiny scales. That's because he wants to be good at hiding in the dark. He's a sneak and a thief. He's thin and snake like. Which you can't really tell here. He's basically everything there is to be in a 'typical' western dragon. He even breathes fire and hordes lots of treasure.
I think the differences work and I hope the descriptions in the book also describe what I've drawn here. Otherwise I'd be sad.

The Ice Drake I imagined as a four limb creature, his wings and hands being the same thing. His face is square and blunt and he's got a nice series of thick wide spikes on his back for armor. Living up in the north where he does he has to deal with Ice Giants which are like polar bears on steroids.

(I haven't get around to coloring this one yet, silver is HARD.)
The Wyrm I went with something rounder. He's not a fighter and he doesn't have to deal with much in the way of dangers. He's a scholar. The Wyrm is also comfortable in the rivers and waterways so he needed a very sleek design. His wings can fold flat against him when he's in the water or act like fins. He has a hording tendency but it tends more to useful collections than straight treasures. Also he's able to part with his treasures if he thinks it will do good.

This guy is our 'traditional' looking dragon. He's very dark colored and doesn't have any shiny scales. That's because he wants to be good at hiding in the dark. He's a sneak and a thief. He's thin and snake like. Which you can't really tell here. He's basically everything there is to be in a 'typical' western dragon. He even breathes fire and hordes lots of treasure.
I think the differences work and I hope the descriptions in the book also describe what I've drawn here. Otherwise I'd be sad.