Begging your pardon, but in what way exactly do you believe them to be different, other than the letters used?
well considering that GMT and UTC are NOT the same, being Military time (which does not always change the same way as GMT and other timezones as it is used on Military and Naval Vessels)
because a lot of companies use UTC instead of GMT (as UTC is actually GMT/GMT-1) and as most Euro servers are based in France/Germany, then UTC is more central to be used (although there are a few companies that have servers in Ireland)
but hey, I'm used to the time difference and compared to EST (GMT+5) its only an hour and barely noticeable a difference
EDIT 2: info for those that want to learn something new and interesting
UTC is used by international shortwave broadcasters in their broadcast and program schedules. Ham radio operators, shortwave listeners, the military, and utility radio services are also big users of UTC. All of the times and dates found here at DXing.com at UTC unless otherwise indicated.
Greenwich mean time was based upon the time at the zero degree meridian that crossed through Greenwich, England. GMT became a world time and date standard because it was used by Britain's Royal Navy and merchant fleet during the nineteenth century. Today, UTC uses precise atomic clocks, shortwave time signals, and satellites to ensure that UTC remains a reliable, accurate standard for scientific and navigational purposes. Despite the improvements in accuracy, however, the same principles used in GMT have been carried over into UTC.
UTC uses a 24-hour system of time notation. "1:00 a.m." in UTC is expressed as 0100, pronounced "zero one hundred." Fifteen minutes after 0100 is expressed as 0115; thirty-eight minutes after 0100 is 0138 (usually pronounced "zero one thirty-eight"). The time one minute after 0159 is 0200. The time one minute after 1259 is 1300 (pronounced "thirteen hundred"). This continues until 2359. One minute later is 0000 ("zero hundred"), and the start of a new UTC day.