With regards to lineart in the image you posted for the side-by-side comparison I noticed a couple of things:
1) The line art was still rough in places. For example at the bottom of the blazer, the line juts out. On the sword handle the lines don't connect. The middle button on the blazer isn't a circle. It's not necessarily a problem because you know you will colour it, but those little details all together can make lineart look a bit off at first glance.
2) In your sketch you are thinking much more 3D - there are volumes. But it's almost like you forget about that when you get to the lineart stage. For example, the sleeve on the arm that holds the sword down has no creases to reflect the fact that her elbow joint is slightly bent. Or the tie doesn't curve round her breasts at the bottom, it goes straight, which makes her chest look flatter. On the other hand, if you look at how you did her legs and socks - those look much more 3D! It's almost as if you are good at picturing naked bodies in 3D but not the clothes on top?
3) The sketch has a variety of line thickness but the lineart doesn't. That's not a bad thing, but can also contribute to the feeling that the sketch looks "better" than the lineart because it's more interesting/dynamic in terms of lines. Don't let it bother you. You know you will be colouring it in so it's not going to look like the line art forever. I went through a phase of trying out different thicknesses for lineart and never got the hang of it properly (some artists do) but I found that actually doing quite thin lines as you are doing and then doing a smashing job with the colouring gives the character sprite all the life it needs.
Also, I was just wondering if you use the trick where you flip your canvas horizontally? You probably do, but thought I'd mention it just in case. I find this really helps with the lineart stage because I can see where things are a little wonky.
The other thing I find that helps with lineart is to use 2-3 layers at the same time, so that I can connect two swipes (let's say on the V of the blazer) and then erase the "leftovers" without going into the other line. It gives it overall a more solid feel because not every line stroke ends in a taper.
One other thing that's noticeable is that your hands don't have consistent proportions. I find it helps to think of a hand (outstretched) as being roughly the size of the character's face. So if they put their palm to their chin, their finger tips would just reach the hairline. Obviously your style goes for more "babylike" proportions, so you could probably get away with having hands a bit smaller, like from chin to eyebrow. Try a few and see what you think!
I have also done a load of studies on hands where I drew them in isolation from different angles etc. You can do this using your own hands as reference or look up reference online. But practice does really help - I'm sure you'll see a big leap forward with hands if you did!
Some examples of other people doing hands studies to give you inspiration! ^_^
https://taileendenvers.deviantart.com/a ... -341963756
https://emisuzu.deviantart.com/art/prac ... -189660589
(I should add that clearly your drawing of hands is getting better and better with each picture and more consistent too! So keep it up, you're already halfway there!)
Anyway, hope this helps!! ^_^
Warm wishes,
Steamgirl
