The Echelon position is the basis of many different formations. All airplanes fly at the same level, one plane’s wing at 1.5 meters from another plane’s horizontal stabiliser.
A special part of the Echelon position is the Echelon turn. In a normal formation turn, the outmost airplane flies highest and the innermost airplane lowest. Echelon turns are different: all planes at the exact same moment and remain at the same altitude. You can see how on the rightmost photo below!