Absolute risk maybe arrived at in relation to the initial investment; whereas relative risk is measured in relation to any benchmark index / benchmark reference point. It is always in comparison to some other benchmark or asset.
Example: An investment of INR 100,000 may decline to INR 50,000 as a result of decline in price of the asset. Hence, there is an absolute negative return of 50%.
However if the index or the reference benchmark has fallen by 65% during the same period of time; then the relative return on the asset or the instrument is better compared to the return on the index or that reference benchmark.