Someone JUST asked me if I was JW because I do not accept the traditional view of eternal conscious torture in Hell. The JWs that came to your door were correct, the Bible really does teach that the wicked will perish and will be no more, in other words the wicked will cease to exist after the judgment.
But I am NOT JW, and here is why. (And this will answer your question about the main difference between JWs and Christians)
JWs do not believe that Jesus of Nazareth was and is truly God. I absolutely believe that Jesus Christ IS God, Fully God and also Fully Man. I believe that the Bible is absolutely clear on this, and this one point removes the JWs from Christianity. If someone does not believe that Christ is truly God, how can they also claim to be Christian?
I guess this is why I get so offended when people ask me if I'm JW. If Jesus of Nazareth is not truly God, then His death on the cross is of no effect for me and the rest of us. Then we will still owe the penalty for sin on Judgment Day. The wages of sin is death, so we would all perish on Judgment Day if Jesus is not truly God. My faith is in Jesus Christ.