As the title says, I am confused about the difference. From my understanding both allow you to own a share of a company without owning a full share.
unit linked investing
As an individual to mitigate risk one would invest in Mutual Fund, ETF or similar constructs [unit linked Life Insurance, etc].
The concept being you invest in small amounts and the fund then invests into actual shares. In theory you own a fraction of all such shares.
This is slightly similar concept, but works on single share. If one does not believe in any of the Mutual Funds and their underlying stocks but want to invest directly into shares; the funds required would be large. So if you want to buy something, you pool your money with other like minded individuals and buy a fraction of the share.