Small Corporate jets such as the Cessna Mustang, or Embraer Phenom seat 4 passengers. These jets are often flown by the business owner, or a single professional pilot. They are used for shorter distance flights.
Mid-sized corporate jets have a larger seating capacity than the small corporate jet, usually in the 7-10 seat range. Normally these jets would be piloted by a professional two pilot crew. Cessna Aircraft Company manufactures the Cessna Citation line, which includes many models of mid-sized jets.