Distinguish Between Soft and Hard Superconductors

These are also known as Type I and Type II Superconductors.

Soft and Hard Superconductors
Soft or Type I Superconductors	Hard or Type II Superconductors
Soft superconductors are those which can tolerate impurities without affecting the superconducting properties.	Hard superconductors are those which cannot tolerate impurities, i.e. the impurity affects the superconducting properties.
These are low critical field.	These are high critical field.
These are show complete Meissner effect	Hard superconductors trap magnetic flux and hence Meissner effect is not complete.
In these types of superconductor current flows through the surface only.	In these type of superconductors, current flows throughout the material.
Eg. Tin, Aluminium	Eg. Tantalum, Neobium