There are different time zones in the world, and those time zones are meant to be used in determining the actual time of a particular place as the mean sun passes through the Greenwich Observatory. GMT and BST are examples of those time zones. GMT is the short form of Greenwich Mean Time. It is considered to be very similar to the Coordinated Universal Time. GMT was first used in the United Kingdom and later adopted the use of an invented mean sun to improve the accuracy of the time. Today GMT has used a standard time zone in calculating the time difference of other countries or places. BST, on the other hand, is the short form of British Summer Time.
It is the time zone used in the United Kingdom during the summer. It can be calculated or determined from GMT by adding an hour to GMT. Another important information is that, while both GMT and BST are used in the United Kingdom, GMT is used during winter while BST is used during summer.