Investing in debt-based products gives you the beneficial rights of a lender and allows one to receive fixed interest and principal payments that are independent of asset value and rents. Even if the asset doesn't generate revenue, you will continue to receive interest and principal payments. You will not be able to participate in capital appreciation or rent growth.
Investing in equity-based products gives you the beneficial rights of an owner and allows one to enjoy all the capital appreciation, rental yields (if any) and control over the portion of asset owned.