I can understand why no one has answered your question as yet, because Hinduism and Islam have completely different origins, in completely different regions. Scholars have yet to dig up any certain reasons for the beginning of the Hindu religion. It dates back to the prehistoric Iron Age at least.
The reason why Islam was started is that its founder, Mohammed, was against his tribe (the Koreish) showing too much tolerance for the gods of the people they traded with. He declared that religion should return to the one God of Abraham and so Mohammed was preaching basic Judaism while still preaching his opinion that some Jewish beliefs and practices were corrupt.
Hinduism affected the area where it was practiced by creating a strict caste system while blending in worship of natural phenomena like most pagans do. They have specific gods which preside over specific natural domains. The main impact, though, was the very strict caste system.
Islam affected the society where it was practiced by reforming some of the practices of the other two Abrahamic religions (Christianity and Judaism. They provided a daily recitation as a reminder to its believers exactly what the mission is expected to be. This recitation is known as the Koran, and it's never been used as a sort of Bible the way Christians use their scripture or the Jews used theirs.
The Koran wasn't put into writing until after the death of Mohammed. This attempt at a higher morality appealed to many people, particularly those ruled or conquered by Rome, which at the time was viewed as highly corrupt.and immoral, and that's why it also spread quickly. It was not the case of Muslims being particularly murderous.
Even though there were differences between Shiite and Sunni Muslims, the first Islamic Empire caused the development and preservation of ancient sciences, and this in turn sparked the Renaissance in Christian Europe during a time it had plague epidemics.
The Empire gets credited for translating a great deal of the knowledge from the great Alexandria Library before it was demolished by the Christians, and the Empire was the first to benefit from the medical discoveries made by ancient Greeks. The plagues, which all but killed off all the Christians, clearly did not kill off the Muslims. Scientific advancement was the mark of the Islamic Empire. It was first governed from Damascus, and then finally from Baghdad.
The Mogul invasions demolished Baghdad, and so put an end to the Islamic Empire. The later decline of the Mongol hordes also paved the way for the success of the Turk invasion (3 major Turk tribes involved), and as they converted to Sunni Islam, thus also converting the vanquished Mongols in their midst to Sunni Islam, the Shiite-Sunni rift became more pronounced, and more bloody.