When Obama refers to “social justice” he is lamenting the truth that some people are better off than others. There are the very rich and the very poor and that to him is the great injustice. Obama, I think sincerely, seeks to eliminate that inequality,an inequality of status.
Opposing thinkers do not use the term “social justice”. But if they did it would be defined as equal treatment. To create equal status you must take from the haves and give to the have-nots. This is not equal treatment. It requires force or coercion against one individual and charity to another without regard to merit. It is a great injustice.
Equal status vs. equal treatment, that is the Great Divide.
“A society that puts equality- in the sense of equality of outcome – ahead of freedom will end up with neither equality nor freedom. The use of force to achieve equality will destroy freedom, and the force, introduced for good purposes, will end up in the hands of people who use it to promote their own interests” Milton Friedman