This is the increase from a cost (the contractor pay rate in recruitment) to get to the sales figure (client charge rate). This is a common pricing strategy within the recruitment sector.
Margin and Mark up are often used interchangeably, and sometimes incorrectly!
Margin is reflected as a percentage of the sales price, whereas Mark Up, as the name suggests, is based on the % increase from the cost price.
Raise advance the full agency commission, direct to the agency ahead of the end-client paying their invoice.