eKeyPad Versions


I am finding the app stores descriptions to be extremely vague for all of the different versions of eKeyPad out there.. does anyone have a cheat sheet?

For example, I see:
eKeyPad ISY - ISY control (I own this one so I know what it does)
eKeyPad Alarm - basic M1 control (my assumption the goal here is to strip out the "noise" for actual users?)
eKeyPad M1 - unsure how this differs from Alarm?
eKeypad Pro - again, unsure how it differs from M1 (maybe customization? though M1 also identifies customization as a feature)

I guess I am really confused on M1 versus Pro. The descriptions in the app store really seem similar to me.