Outpatient surgery is when you have surgery and you are not admitted to the hospital in the process. You are released the same day. Most times you need someone to accompany you home after the surgery. Regular surgery is when you have the surgery and are kept in the hospital overnight.
He maybe be using them interchangeably, meaning outpatient surgery. Some surgeries (or "procedures" as they're called these days) require hospitalization while others do not. The ones that don't are outpatient.
If someone has to have surgery, it will require a hospital stay til doctor okays discharge. Out-patient surgery does not involve hospitalization. It is a surgery, but can be performed in doctor's office or hospital and patient can go home the same day with some medication and advice from doctor to follow.
Out-patient surgery takes place in your doctor's office. You come in at the scheduled time, get the procedure, and go home. Regular surgery takes place at the hospital and you stay at least one night, sometimes several.
