What's better - a Chapter 7 or 13 Bankruptcy?

I am going through a hard time and after having good credit need to file BK unfoortunately. The attorney quoted $3,000 to file for 13 and $2,000 to file for 7 so I wanted to know why one is 1/3 cheaper. I read online that the 13 says you have to repay the debt, so what would the point of filing BK be if i don't have the money after I lost my job to pay it? This is in CA if that makes a difference.