1, The full form of EST is Eastern Standard Time. It’s used on Regional ,Time Zones in Worldwide

The Eastern Time Zone (ET) of the United States and Canada is a time zone that falls mostly along the east coast of North America. The clock time in this zone is based on the mean solar time of the 75th meridian west of the Greenwich Observatory.In the United States and Canada, this time zone is generally called Eastern Time (ET). Specifically, it is Eastern Standard Time (EST) when observing standard time (winter), and Eastern Daylight Time (EDT) when observing daylight saving time (spring to autumn).

2, The full form of EST is Energy Saving Trust. It’s used on Associations & Organizations ,Non-Profit Organizations in United Kingdom

Energy Saving Trust is a non-profit organisation jointly funded by the British Government and the private sector in order to help fight climate change by promoting the sustainable use of energy, energy conservation and to cut carbon dioxide emissions in the United Kingdom.