[Joisu]

I hear in a lot of anime and Japanese songs. I know that both of them means "we", but what is the difference between the two? At first, I thought that only boys use 'bokutachi' but in a lot of Japanese songs sung by girls, they use 'bokutachi' also....(Example: Every Heart by BoA)

Anyone can tell me the difference? ^_^;;

Also, is 'kimi' and informal way of saying "you"?