Conformational isomerism is defined by rotation about sigma bonds and does not entail variations in bonding connectivity or geometry.
Two or more structures classified as conformational isomers, or conformers, are basically just two of the same molecule that differs only in the angle about one or more sigma bonds.
Confirmation is the spatial arrangement of carbon and hydrogen atoms that can be transformed into one another by rotating around a single bond.
Staggered Confirmation:
When hydrogen atoms bonded to two carbons are as far away as feasible from each other, staggered confirmation occurs.
The staggered conformation is more stable than the eclipse confirmation because there are fewer repulsive forces and energy due to the multiple separations between the electron clouds of bonds.
Because the electron cloud of the carbon-hydrogen bond is the greatest distance apart, the staggered form of ethane has the least repulsive forces, the least energy, the least torsional strain, and the greatest stability.
Figure: Staggered and Eclipsed Conformation of Ethane
Hence, the staggered form of ethane has minimum repulsive forces and minimum energy.
