What is the difference between screenshot and screencap in adb shell?

Question

I have a Galaxy S i9000 with CyanogenMod 10 on it which supports both of these commands in adb shell and both take screenshots. They look a little different however.

Using adb shell screenshot:

And using adb shell screencap:

It seems that adb shell screenshot lacks one colour channel, whereas screencap shows all the channels. I tried the same experiment on a Galaxy S4 with 4.4.2 KitKat and only screencap worked, leading me to believe that screencap is a newer version of screenshot.

Answer 1

screenshot worked directly with the framebuffer which is no longer supported in the recent Android versions

screencap is the new version of the tool which works through the SurfaceComposer instead.