What is the Difference between Percentage Complete and Percentage Physically Complete

In Microsoft Project there are two ways to  define Task completion. One is in terms of Percentage complete and second is by Percentage Physically complete. See below screenshot showing "Physical % Complete" and "% Complete". 

What is the difference between these two? Which Percentage completion should one report?

Figure: Above screenshot is from Microsoft Project 2016  (Click on above screenshot to see clearly)

The Percentage complete is reported in terms of time. 

However, this reporting may not be true representation of the actual work completed. For example, if the work performed is similar and has same steps and takes the same amount of time, then this reporting may work. However, in practical projects, as work is performed there are some tasks that take more time and resources and there are some tasks that take less time and few resources. Hence reporting in terms of time may not be an accurate representation of the work completed.

The Microsoft Project Management defines this in an easily understandable way.

Description    The Physical % Complete field shows an entered percent complete value that can be be used as an alternative for calculating budgeted cost of work performed (BCWP). This field is also known as Earned Value % Complete.

Best Uses    Add the Physical % Complete field to a task view and enter values when the calculated percent complete would not be an accurate measure of real work performed or measured. Unlike the % Complete field, the Physical % Complete field is independent of the total duration or actual duration values used by the % Complete field to calculate BCWP.

Example    A project of building a stone wall consists of 100 stones stacked five high. The first row of 20 stones can be laid in 20 minutes, but the second row takes 25 minutes because now you have to lift the stones up one row higher, so it takes a little longer. The third row would take 30 minutes, the fourth 35 minutes, and the last row takes 40 minutes to lay—150 minutes total. After laying the first three rows, the project could be said to be 60 percent physically complete (you laid 60 of 100 stones). However, you only spent 75 of 150 minutes, so in terms of duration, the job is only 50 percent complete. You add the Physical % Complete field to the Gantt Chart view to enter and track progress for this task.

Depending on how you get paid for the work or how the value is earned (by the stone, or by the hour), you can choose the percent complete value or the physical percent complete value to properly reflect this in the earned value analysis.

Remarks     While the default earned value method field is % Complete, you can change it to Physical % Complete for any tasks that apply.

You can also set the earned value method for a task in the Task Information dialog box.

You can set the default earned value method for all new tasks in the Project Options dialog box. You can also choose which of the 11 available baselines should be used for earned value calculations.

The Physical % Complete field is available by default on the Tracking table.

References
Microsoft Project Management Physical Percentage Complete