UTC and CET
The primary difference remains to be the fact that GMT is the denomination of a timezone, while UTC is the title of the time standard.
To calculate the UTC time, the atomic clocks with frequency cycles are used to display the accurate measurements of time. Nevertheless, same as for GMT, the primary purpose of UTC is to denote the universal time zone in relation to others.
The utilization of UTC is peculiar to the coordination of time on the Internet and for Network Time Protocol (NTP) to regulate time of the computers in the world 5. This time system would allow having one measurement of time for the accuracy of connection within the networks. In addition, for the high-precision and universal time across the world, aviation use UTC 24-hour time standard (Zulu time)
CET vs GMT
1.GMT and CET are both time zones. However, the GMT has broader applications compared to the CET. It is basically the point of origin for all time zones which includes the CET.
2.The CET is applicable to 31 countries while the GMT is applicable to all countries in the world. It is actively used in the United Kingdom (for five months) and Iceland (for the whole year).
3.Both CET and GMT switch to another time zone after five months. The switch is done for the summer because the summer season has an extended length of daylight and results in more business and work hours. The CET switches to 4.CEST (Central European Summer Time) and GMT change into BST (British Summer Time).
5.The GMT is known by many names: Greenwich Mean Time, Greenwich Meridian Time, Universal Coordinated Time, international time, military time, precision time and British Standard Time.