In or not?

I was just thinking about this, and wanted to write it down, otherwise it would probably just pass on by like some other thoughts.

John 3:16 "For God so loved the world, that he gave his only begotten Son, that whosoever believes in him shall not perish, but have everlasting life."

What is the difference between believing in him and believing him?

Recently, I read through James, and a lot of it talks about faith vs. works, etc. I came to the conclusion that faith in God, real faith, is having faith enough that I believe what he says enough that I do it, and that is why works shows faith, and faith without works is dead. Is that right?

My question is this: is it the same thing to believe in someone and to believe someone? When we say we believe in Jesus and are saved, is that equivalent to believing what he says? Recently, because of my reading from James, I've felt that if I sin, its showing that I don't really have faith in God. Because if I did, I would do what he says, which is not to sin. Is that the belief in Jesus that causes me to be covered by his blood, which saves me? Is that what James says? Or is it just belief in his death and resurrection washing away my sin? Are the two inextricably linked faiths, actually the same thing, or two different types of faith "in" him?