1. A conformation of an acyclic molecule is a specific disposition of atoms in the molecule in space within the molecule due to free rotation around bonds.
eg: ethane (CH3CH3)
Due to free rotation around the carbon-carbon bond, the ethane molecule could assume an infinite number of conformations, two of which are shown below as saw-horse formulas.
In other conformations of ethane the smallest dihedral angle could be any value between 0º and 60º.
2. A conformation of a cyclic organic molecule is a specific shape the ring could assume.
Due to the flexibility of the ring, the cyclohexane ring could assume an infinite number of conformations, three of which are given below.