First of all, there is no consensus on the number of people who died between 1915 and 1918. The Armenian side pushes 1.5 million, which is silly because the total number of Armenians who had lived in the Ottoman Empire was about 1.5 million anyway. Official number of Armenians who got deported in 1915 was 500,000, 390,000 of which managed to reach their destination, Syria, Lebanon etc.
When you look at the Eastern Anatolia in the years of 1910 to 1920, you can easily realize that it was like a horror movie in there. First Armenian rebels attacked and massacred as many Muslims as they could when they thought it was the right time to side with the Russians and claim their independence, but the reaction that they got from the Ottoman army and Kurdish tribes was as harsh as their own. As many Turks and Kurds were killed in that era by Armenian forces sided with Russians and France. If you go to Eastern Turkey and talk to people they would tell you reversed genocide stories and this is why this issue is not as easy to conclude as the Holocaust.