Some similarities are only to be expected if you agree with Hilaire Belloc that Islam (Mohammedanism) is one of the five great Catholic heresies.
According to Belloc, it sprang from an oversimplification of the main Catholic doctrines, by a pagan who was not a Catholic and it rose up outside the Church.
Mohammed dropped those doctrines that did not suit him. Most importantly, he denied the Incarnation, the Trinity and the whole sacramental structure. From its roots as a heresy, it developed into a religion on its own.