Genesis 7:13
"On that very day Noah and his sons, Shem, Ham and Japheth, together with his wife and the wives of his three sons, entered the ark."
What's the difference? (Honest question, no sarcasm intended.)
On the Noah question, I would answer similar to Cain and his wife question.
On what the difference between magic and God is... I think most people define magic like the genie granting wishes, whereas God grants life, and life that He created. I know it's a leap to see the two as different, but they are really polar opposites. Also when I think of magic I think of something used either for selfish means or maybe for entertainment. God, on the other hand, used his power to lay his life down in pain on our behalf. (Sorry to be so preachy!)