1)The God of Christianity is a personal God, religions have impersonal gods.
2)Religions believe man is inherently good, Christianity believes man is inherently evil.
3)Religions believe in works to be saved, Christianity believes the work has already been done by Jesus. Put another way, with religions it's "do" with Christanity it's "done".
Religions are alike in that they all try to deal with the sin nature of man. They have common themes of moral righteousness and good deeds while shunning evil. Rather they know it or not, it's an attempt to confront the wickedness of human nature.