Hi Gail, the % complete is a function of the amount of duration used, whereas
the % work complete is a function of the amount of work completed. EG, If I
have been given 10 days to build a wall, at the end of week 1 I would be 50%
complete (ie I've used half the time). However, I might actually have
completed 2/3 of the wall, therefore the %work complete is 66%.
Worth having a look in the help file in Project Pro for more information
(and examples)