Basically VMD-EZ151,VMD-EZ152, VMD-EZ153 are first generaton EZCast dongles with separated WiFi module.
VMD-EZ151 is the world 1st EZCast dongle;
VMD-EZ152 was the most popular EZCast dongle, known as M2, and there're many copy dongles in market;
VMD-EZ153 is an OEM item for a China brand
VMD-EZ151i, VMD-EZ154, VMD-EZ155 are 2nd generation EZCast dongles
1. With bulit-in WiFi module and external antenna
2. Improved performance and stabler WiFi connection
3. Cleaner and neater connection w/o the tail of isolated WiFi module.
4. Market in order
More info see the EZCast comparison table here.