Plan Progress vs Actual Progress

Irfan,
Plan Progress is taken from your baseline. If you don’t have baseline assigned by default P6 use current Project. Actual Progress is the % complete that you enter every cut-off date before running schedule (F9) on the new Data Date or status date. You can get the variance of the two by showing Column-> Durations-> Variance - Project Duration or Variance – Project Start Date or Variance – Project Finish Date.

% Planned : % of works planned to be done (from baseline)
% Actual: % of actual work happened (you need to update)

You can insert both the columns and variance as Rodel already explained.

Regards
Balaji