It's really confusing. Just call it "express" and "local" service, with "intercity" or "regional" for longer services.Not something I would be against. Keep the GO brand but you could differentiate the different types of services provided. Here's an example:
GO Regional Express Rail: All-day 15 min electrified service.
GO Intercity: The longer distance services. Ex. Union to Niagara, Union to London.
GO Home: The remaining peak-only services.