Blue and Green lines

I dont mean to sound stupid but what do the green and blue lines mean across the staff members?

they are both XP. the green is the total XP and the blue is the XP you have until the staff member reaches the next level.

Ok thanks

How can you increase the rate staff members get XP? And how do they improve when they reach a higher level? I can\'t see any clear differences when browsing staff members (in the piramid like graphic).