In any scheduling software you enter schedule then save baseline and enter actual information. Find out the difference between these 3 types of information.
This is the planned start, finish and duration of the activity. In any scheduling software we first enter schedule, which is how we want the activities to perform.
Once the schedule has been finalized and approved, we save/create baseline. Baseline is the exact copy of your schedule.
The reason why we create the copy of the schedule is comparison. When the activities start and you want to compare actual start, finish and actual duration with the originally planned information, we use baseline for the comparison.
Note that we do not compare actual progress with the Schedule, although Schedule is also the original plan and that baseline was copied from that! This is due to the reason that schedule gets rescheduled every time we enter actual values. For example, an activity has 10 day duration and until today 50% (5 days) work should be done but only 25% (2.5 days) work is done because the work could not be done due to thunderstorm. This activity will complete 2.5 days (25%) later than planned. Hence, the Scheduled finish date will change. Therefore, we can not compare actual progress with current information, we need to compare with with what was originally planned, and saved, which was in the baseline.
Note that in some scheduling software, baseline was earlier called 'Target'. It becomes easier to understand baseline when we call it Target instead of baseline, since target is what we have to achieve, once the schedule has been entered and activities have started.
This is the real progress of the activities. Actuals should ideally be meeting the original plan (baseline), but this usually does not happen. When the activities start, we enter actuals such as actual start, finish, actual duration, actual man-hours and actual costs, etc. In scheduling software, we usually only enter actual work completed, in terms of duration (effort/man hours), and the software automatically calculates the actual cost, and other actual information based on actual duration/effort/man hours you have entered.