Charter flights are generally operated by smaller companies and the flights are scheduled on particular days of the week E.g. Saturday and Sunday, where the flight leaves only operate on those days and they usually only offer one flight time. Charter seat flights are usually bundled in a holiday package and the seat pitch is usually smaller than on a scheduled airline.
Scheduled flights are operated by major airlines. The large airlines have enormous fleets and set schedules. For example, an airline may fly from Toronto to Los Angeles five times a day every business day at the same time each day.