Social justice is defined as "... promoting a just society by challenging injustice and valuing diversity." It exists when "all people share a common humanity and therefore have a right to equitable treatment, support for their human rights, and a fair allocation of community resources." (...) Social justice is generally equated with the notion of equality or equal opportunity in society. [1]

Justice is, well treating human beings fairly and without Prejudice.

Injustice is for example when Rich kids get better Education and better life chances than Poor kids.