1. Exemtpions are given in the Income Tax Act which are thrust areas of the government (i.e. the areas which the government wishes to boost the particular segments) and/or the earning body is a weaker section of the society and/or requires growth in those activities
2. Deductions are given to boost savings for social welfare and other activities with which the country will be able to get strength in the desired fields.
3. Relief is given when double taxation is there or undue hardship to the taxpayer is there.
These are the major concepts behind the above terms.