Although broadly both these forms refer to Individuals and HUFs having income from business and profession, the difference lies in the following areas
ITR-3
ITR-4
For other than presumptive taxation
Those opting for presumptive taxation need to file ITR 4
Total income reported can exceed Rs 50 lakhs
Total income shall not exceed Rs 50 lakhs
Can be filed by a director of a company
Cannot be filed by a director