That would be the same sprite with several edits made that help you improve it visually. Although I would have left a description of telling OP what changed and what could be changed in the sprite.
ANYHOW.
The sprite itself suffers some anatomy issues, His right leg seems like it's broken and the shoes seem bigger than they really need to be. The contrast of the blue on his ear isn't really enough and there a ton of jagged outlines all over the place that hamper the quality of the sprite more so than anything else. Also I didn't notice this until I compared the two sprites but Sonic's nose should be between his eyes and not have such an offset off his head.
I don't know if you used a reference to look at as you were making this but I think that you should be doing that not just as you're working on sprites or pixel art but with anything you make in general.
Come to think of it, I would also consider adding shading and anti-aliasing, because right now the sprite you made seems very flat and I'm more bothered by that visually than anything else since we're not really looking at a sprite that's 8-bit.
ANYHOW.
The sprite itself suffers some anatomy issues, His right leg seems like it's broken and the shoes seem bigger than they really need to be. The contrast of the blue on his ear isn't really enough and there a ton of jagged outlines all over the place that hamper the quality of the sprite more so than anything else. Also I didn't notice this until I compared the two sprites but Sonic's nose should be between his eyes and not have such an offset off his head.
I don't know if you used a reference to look at as you were making this but I think that you should be doing that not just as you're working on sprites or pixel art but with anything you make in general.
Come to think of it, I would also consider adding shading and anti-aliasing, because right now the sprite you made seems very flat and I'm more bothered by that visually than anything else since we're not really looking at a sprite that's 8-bit.