Your user score is just a number that reflects how active you are here and also how helpful. It really means nothing as a number, but when people see a 90+ next to your name, it usually helps. Also you can become a featured artist with a 100. You are much easier to find as well if you are in the 90s.
Your Hub scores are just how good your hubs are. Are they full of content and helpful text/pics? If so your score will be higher than just writing a paragraph and publishing it. This is the important score. You always want high scores on your hubs, but it isn't necessary as I still have hubs with scores in the 60s that do well.