Superstar actors typically try to obtain contracts that specify that they will receive a set percentage of the total revenue generated by ticket sales, i.e. "the gross".Producers are left with "profits"; i.e. total revenue from ticket sales minus the percent paid to the actors and then minus all costs of production and marketing.

Why might actors want contracts structured that way?

Why might producers be willing to agree to that, and how does this make the goals of actors and producers different?