Simplify the following text for a Grade 12 native English-speaking person.
Original: The Council of Ministers of the Union of Soviet Socialist Republics ( USSR ) ( , tr . : Sovet Ministrov SSSR ; sometimes abbreviated to Sovmin or referred to as the Soviet of Ministers ) , was the de jure Soviet Government comprising the highest executive and administrative body of the Soviet Union from 1946 until 1991 .
Simplified: The Council of Ministers of the Union of Soviet Socialist Republics ( USSR ) , ( sometimes shortened to Sovmin or Soviet of Ministers ) was legally the Soviet government . It was the highest executive and administrative body of the Soviet Union .