Editors Question:

both do the same task..! in the sense :wq,:x and ZZ
are used to save the changes of edited to storage and quit..
but to jot down the difference a foolish one.. :wq and :x
requires <enter> key to be pressed to fire this commands
where as ZZ works as a shortcut (hot) key.. it some what
like for prior commands we are requesting Vi to do the work
and later command we are telling/commanding