I was curious about the time difference of prayers between Sunnis and Shias. I was talking to my Sunni friend and he said that Fajr for them was at 4:23 AM meanwhile Fajr for the Shias is at 5:01 AM ( I live in the city of Edmonton), why is there a huge difference for Fajr prayer between Sunnis and Shias?

We Shia go by:

1- The “True” Fajr, which occurs when a horizontal white light appears in the eastern horizons, and then slowly rises into the sky. Some sunnis go by the “false” Fajr, which occurs before the true Fajr, as it occurs when a vertical while light appears in the eastern horizon.

2- When we have certainty that Fajr has set in. In cities that have a high latitude, figuring out Fajr is challenging, so we can only pray when we are certain it’z Fajr.