Liberation Theology: First off, the "liberation theology" we're talking about when we refer to South American Catholicism is distinct from the American "black liberation theology." They trace their roots back to two different commonly-cited foundational texts: James H. Cone's A Black Theology of Liberation, and Gustavo Gutiérrez's A Theology of Liberation, both written in the early '70s. The two theologies definitely share some significant similarities, namely a reading of scripture that puts the emphasis of the Christian concern with sin on social problems, rather than individual ones. In other words, Christians adhering to a liberation theology should orient themselves toward action against oppression. More symbolically, liberation theology argues that God identifies with the oppressed, and that Christianity should take upon itself the lens of the poor. Both theologies are also often derided as "Marxist" by conservatives (remember Rev. Wright?)
On the surface, this theology would seem to fit with Pope Francis. Here's the New Yorker, summing up his approach to poverty as a Catholic:
"He has made some sharp remarks about the vanity, self-infatuation, careerism, and pursuit of promotions in the Roman Curia. As Archbishop of Buenos Aires, he apparently preferred to be called Father Jorge, and was known for his preoccupation with the city’s poorest, reportedly washing and kissing the feet of patients suffering from AIDS."
But Francis has opposed liberation theology in Argentina. According to the National Catholic Reporter, this seems to have to do more with keeping Jesuits from becoming politically active or working directly in community groups