Plane stress :
The plane stress is the case in which stress is zero in one direction. In this case stress is in 3 directions.
In plane strain case, strain is in 3 directions and in one direction strain value is zero.
Normal or Direct stress :
The stress which is applied by us intentionally is known as direct or normal stress.
Induced stress :
This is the stress which we do not want to produce but is induced due to direct or normal stress.