Why is there a difference in time?
The time difference between countries is caused mainly by the Earth rotating on its axis. This causes a complete rotation every 24 hours, which results in a time difference between locations on earth.
The earth has a part that faces the sun and another that doesn't. As a result, the part facing the sun is daytime, and the part that does not see the sun is nighttime.
It may seem like an easy matter, but the truth is that it isn't. In a country, there could be a part facing the sun, and another not touched by the sun. Therefore, some parts may be daytime, and others nighttime.
The sun does not have the same timing. This is because the sun rises in one city faster than the other, and sets in both cities at different times. Therefore, it is difficult to unify the time between cities even if they are located in one country.