Difference between Sigma and Pi Bond

The following are the points of difference between Sigma and Pi Bond.

Sigma Bond	Pi Bond
This bond is formed by the overlap of orbitals along their internuclear axis (end to end overlap).	This is formed by sideway overlapping of orbitals (lateral overlapping).
This bond is formed by overlapping between S-S, S-P or P-P orbitals.	This bond is formed by the overlap of P-P orbitals only.
Overlapping is quite large and hence Sigma bond is a strong bond.	Overlapping is to a small extent. Hence Pi bond is a weak bond.
There is a free rotation of atoms around the Sigma bond.	There is no free rotation of atoms around the Pi bond.
This bond may be present between the atoms either alone or along with Pi bond.	This bond can never be present alone. It is formed after the formation of the Sigma bond.
The shape of a molecule is determined by Sigma framework around the central atom.	The shape of a molecule is not determined by the Pi framework.
Electron cloud in this case is symmetrical about the line joining the two nuclei.	Electron cloud of Pi bond is unsymmetrical.
Sigma bond consists of only one electron cloud, symmetrical about the inter-nuclear axis.	Pi bond consists of two-electron clouds, one is above the plane of atomic nuclei and the other below it.