The accounts of Jesus were written 15-60 years after the death and Resurrection of Jesus by eyewitness and friends of the eyewitnesses. Matthew and John were eyewitnesses. Mark and Luke got their information from the eyewitnesses.
When you look at what we have historically and what Islam has historically, there is no comparison. Islam was written 200-300 years after the death of Muhammad by no eyewitnesses or by people who never knew him, nor even lived in the same country he lived. That is why we can know exactly who Jesus was and what Jesus said.