CSGO is a open market for different organisers to ply their trade. As a result of this and since there are no ground rules set by Valve on how organisers should run their tournaments, we have seen many disparities between the way the tournaments are run between the organisations.
One small difference has been pointed out by Skadoodle. Different organisers have set different timings for the round start delay time. It is the time which is spent before the round starts. Ensuring a common time for all tournaments means that players can buy their weapons in time and have enough time to discuss strategies regarding the next upcoming round. If there are different times, players often get confused as they are accustomed to something else in the meantime.