What is the difference between firm reservation and preferential reservations?

• Firm reservations: As per the SEBI regulations to describe a fixed portion of shares is set aside for specific eligible groups. It is a must to clearly define in the DRHP/RHP, allotment rules follow SEBI guidelines.
• Preferential Reservation: Preferential reservation is a concept of giving preference to a certain group of eligible investors.

In both the reservations, shares are not available to the general public, which affects allotment chances.