Sean McDowell recently wrote this article for Biola Magazine explaining the key differences between Mormonism and Christianity.
McDowell posits that Mormonism is distinct from Christianity by placing an unnecessarily heavy burden on its followers, offering a different understanding of faith (fideism), the possibility of becoming a god, a rejection of original sin and the idea that God the Father has a physical body.
Because of the length of the article these issues aren’t addressed in a great amount of detail. The comments section was almost immediately filled by Mormons claiming inaccuracies and libel and demanding a retraction. Personally I think the article is accurate of the mainstream Mormon view. I feel like many of the commentors are offended that anyone other than the LDS church is describing Mormon theology rather than from any inaccuracies in the article itself.