The simplest way to find out the difference in the time between any two cities in any country of the world is to use the time zone which is used as the international standard time zone, namely the Greenwich Mean Time. The Greenwich Mean Time is abbreviated as GMT.
To use the simplest method to find out the difference in time between the time in the city of San Francisco in the state of California in the United States of America and the time in the city of Miami in the state of Florida in the United States of America, it is advisable to take 12 noon Greenwich Mean Time (that is 12pm in the afternoon in the United Kingdom) as the standard time. The city of Fresno in the state of California in the United States of America is eight hours behind GMT and the city of Miami in the state of Florida in the United States of America is five hours behind GMT.
Therefore, if it is 4am in the city of San Francisco in the state of California in the United States of America and 7am in the city of Miami in the state of Florida in the United States of America, it means the time in the city of San Francisco in the state of California in the United States of America is three hours behind the time in the city of Miami in the state of Florida in the United States of America. In other words, the time in the city of Miami in the state of Florida in the United States of America is three hours ahead of the time in the city of San Francisco in the state of California in the United States of America.