What is the different in Earned Value Calculation options for percent complete?

Activity % Complete: Choose to calculate earned value according to current activity completion percentages.

Use WBS Milestones: Choose to calculate earned value by defining milestones at the WBS level and assigning a level of significance or weight to each of them. As progress occurs and you mark each milestone complete, the WBS element’s performance percent complete is calculated based on the weight of the milestone.

0/100 % Complete: Choose to calculate earned value as 100 percent only after the activity ends.

50/50% Complete: Choose to calculate earned value as 50 percent after the activity starts and until the activity ends. After the activity ends, the activity's earned value is 100 percent.

Custom% Complete: Choose to calculate earned value as a percentage you specify. This percentage applies after the activity starts and until the activity ends. After the activity ends, the activity's earned value is 100 percent.