Santiago is 2 hours ahead of Medellín
Best overlap: 8:00 AM to 4:00 PM in Medellín is 10:00 AM to 6:00 PM in Santiago.
8:00 AM to 4:00 PM in Medellín is when Santiago is also working, at 10:00 AM to 6:00 PM their time. Santiago is 2 hours ahead of Medellín, and with 8 hours of overlap you can even run back-to-back calls without stepping outside business hours. The window above shifts seasonally: Santiago keeps daylight saving while Medellín ignores it.