Hi Jitu,
Thanks for your reply. Sorry for the delay but I have seen your message just now that I discovered the function of pause by chance by myself and I want to post the answer.
In my case, I recorded a mapkey for changing the format of a drw, and I saw that there is a difference when the mapkey, once selected the format, encounters the input bar that appears on the top (in my case for surface_treatment parameter to put in the .drw title block):

Pause for keyboard input --> the mapkey pauses in order to allow the user to write in the bar everytime the mapkey is executed. After having clicked on the green mark, the mapkey goes on with its recorded script.
Accept system defaults --> the mapkey at each execution accepts whatever is already written in the bar (in my case it is empty, if there is something already written it is highlighted in black), and clicks the green mark by itself. Then goes on with its recorded script.
Record keyboard input --> the mapkey records and will use forever what the user writes in the bar at the moment of mapkey recording: so I write "quenching" during mapkey recording, the mapkey will always write "quenching" when it encounters that field.
Hope to have been quite clear for others who might read,
and would be interested to know if anyone has found this difference in other contexts other than Jitu's too.
bye