If you asked this question to 10 different girls you will get 10 different answers, i will give you my definition of the 3.
A escort, ( in my opinion) is a person willing provide a service in return for compensation, with no strings attatched and lasting usually no more than 1 - 2 hours.
A Companion (in my opinion) is a person who acts as your personal companion for a period of time usually 3 hours to 3 days. compensation is usually money or gifts.
A Vip Companion (in my opinion) is a companion who provides more intimate, discreet and enjoyable time with a client like Trips, Operas, Concerts, Quiet dinner dates, Small vactions. You will get to know that person more intimately and sensually, one who provides companionship and special attention to that one client.
