See back Effect: -
When a pair of dissimilar metals are joined at one end (junction, J1) , and there is a temperature difference between the joined ends and the open ends ( junction , J2 ), thermo-emf is generated, which can be measured in the open ends ( J2 or cold junction).
Peltier Effect: -
The Peltier effect is a temperature difference created by applying a voltage between two dis-similar metals connected to a sample of semiconductor material.
OR
The Peltier effect: Heat is given out or absorbed when an electric current pass across a junction between two materials.