It's hard to explain, but they're two different things. The best way to improve is to practice in such a way that can only be described as boring and pedantic. Slowly, with a metronome, making sure every single note is in tune, every note is properly vibrated, every phrase and direction is properly conveyed, both by itself and with respect to what is happening around it. However, that does not necessarily make practicing boring. It only does if you're not into music enough and/or don't see an end (eg an eventual finished and polished product you can perform) in sight. I find a lot of the music majors at my school just plain aren't into music, which is odd. It seems blatantly obvious even to me, an outsider of music (I didn't even intend on being a music major until I randomly got the acceptance letter and was like that seems interesting), that you will have to love music enough to practice 6+ hours a day straight, and people just don't seem to get that.