Techniques for appraising capital investment are ! payback period, NPV, IRR etc. My question is that what is the difference between NPV & IRR?

Difference between I R R and N P V

While both the I R R and N P V try to do the same thing for a company, there are subtle differences between the two that are as follows:

While N P V is expressed in terms of a value in units of a currency, I R R is a rate that is expressed in percentage which tells how much a company can expect to get in percentage terms from a project down the years.

N P V takes into account additional wealth while I R R does not calculate additional wealth

If cash flows are changing, I R R method can not be used while N P V can be used and hence it is preferred in such cases

While I R R gives same predictions, N P V method generates different results in cases where different discount rates are applicable.

Business managers are more comfortable with the concept of I R R whereas for general public, N P V is better for grasping.