Is your friend blind? Of course you're improving. Just by comparing those two pieces I can see you're gaining skill in proportion, anatomy, and gesture. Your work looks more controlled and confident, and it looks like you put more effort into meticulously working out what looks "right".
Keep working on this skill. It's a good one to have. This is a good rate of improvement, but you definitely need more study sessions to get a better understanding of perspective and proportion. Study sessions really pay off. Art skills (and skills in general) take about a decade of work to get really really good at. I'm nearing 12 years (from age 8) of serious work and I'm just now starting to feel satisfied even though I have so many things to beef up still.
The best advice I can give you is to do those study sessions to better understand figures. I say this because your second drawing is very "stiff" in comparison to the first. You look like you had a lot of fun in the first one and cared more about the act of drawing rather than the actual picture. This helps them look more natural and makes the drawing look better overall. If you do study sessions and have a better understanding, you don't have to concentrate as much and can have more fun. This makes a major difference in your art. Yes, this is "practice", but as long as you continue to love drawing, your experience will make your art improve regardless of how hard you concentrate on getting everything right. You don't have to perfect every mistake, you just have to make it look intended. This is also known as style.
