Initially most funds operated 2 or 3 different plans.
- Regular [Read meant for Retail]
- Super Institutional
Although all these invested in the same / similar underlying type of assets, the Mutual Funds kept the expense ratio low for the Institutional Funds and slightly higher for Regular. Further the entry, i.e. Minimum amount to be invested into Regular was kept low and that for Institutional kept very high.
The way Mutual Funds were trying to play out was, attract large money and indirectly promise them low expense ratio to get more funds invested. While ignore the Retail investor.
SEBI has hence [quite some time back] asked all Mutual Funds to Stop this. So essentially now there is no difference. i.e. an individual can invest in Institutional fund as well. The minimum entry is also nominal as prescribed by SEBI.
Most funds rather than going through name change ... kept the name same, i.e. you can still see "Institutional", "Super Institutional" in the name, but they are like "Regular" there is no barrier left.