I hope this helps, Amin
Schedule Percent Complete (Sch % Cpl) is calculated for every activity (and then rolled up tp wbs and project levels) by comparing the progress of your activities in your current project to the way they were supposed to progress as stated in the approved project target (baseline)
in other words current project vs. the vision at the begining of the project (initial baseline) if still the case or in the target for the current reporting interval (last update baseline) depending on which is assigned as project baseline, assuming you have created and assigned one such target and the activity existed at the time (comparison based on Activity ID). otherwise the Current Project itself is used as baseline.
for example let's take a Data Date of your current project of let's say Nov 11th (project is progressed as of Nov 11th)
BUT the activity bar positions taken into account are not those in the current project (progressed as of Nov 11) but those in the assigned project baseline (target), let's say according to the target set at the begining of the month (Prj BL DD = Nov 1st).
in other words, using Prj BL Start & Finish dates instead of Start & Finish dates. (you can make the baseline bars appear in the bar chart if you want)
depending on where the current project DD intersects (or not) the baseline project activity bars you get your Sch % Cpl
(that is then used when calculating PVC - Planned Value Cost and SPI - Schedule Performance Index)
Sch % Cpl = 0 if the activity was not supposed to start by Nov 11th
(CurrPrjDD < Prj BL Start)
Also the case if the activity has no counterpart in the baseline and was inserted after Nov 1st (the Prj BL DD)
...
Sch % Cpl = 100 if the activity was supposed to finish by Nov 11th
(CurrPrjDD > Prj BL Finish)
There's also the Duration % of Original computed still based on the assigned baseline and this can excede 100.
Current Project Actual Duration / Baseline Original Duration * 100
The Duration Percent Complete (Dur % Cpl) for every activity is computed in the current project as of its own DD alone and regardless of any baseline assigned (if any).
as Orig Dur - Rem Dur/Orig Dur *100
0 % as long as Remaining Duration is equal or greater than Original Duration (not from BL)
Rem and Original are linked for Not Started activities. Remaining Duration may or may not decrease with the increase of Actual Duration and is re-estimated dinamically once the activity is started.
100% once Remaining duration is made 0 by providing an Actual Finish.
The two percent completes are the same for any given activity (and rolled up to wbs, project and even EPS level) only if that activity (all activities contained within the work packege) progress exactly according to plan.
(Progress Spotlight + Tools/ Update Progress up to the desired new DD).
like that is likely to happen. we would be out of a job 
You can use View/ Hint Help for quick definitions and formulae of the different data fields (available columns in the tabular part of the different Primavera windows). annoyng but sometimes useful.