MP4 file format is the most used video file for any portable media player. Whereas this file format is designed for small video output device such as mobile phone, tablets etc. This file format is compatible in many devices like iPad, iPhone, other iOS devices; Android supports this video file format. But when it comes to playmp4 file in your QuickTime you face a compatibility issue.  Sometime we face issue in playing MP4 video such as if you are using Apple device then you might face issue while playing the file. MOV file is the other file type which is widely supported by devices and operating systems just like MP4. This file format is developed by Apple as a standard for playing video apple devices.