Literary criticism and literary theory are said to be not identical with each other. How are they different?

Practically speaking, from a student's point of view,
literary theories are different ways of analyzing literature.  Literary theories are
perspectives one brings to literature when one analyzes, or "criticizes,"
literature.

For instance, one might study medieval
Arthurian legends from a feminist perspective, feminism being one literary theory.  One
might find that Arthurian legends present women as either Virgin Mary-like beauties
(Madonnas) or scapegoats for society's ills.  Women are either put of pedastals and
idolized for their beauty and purity and destined to be rescued by men, or are impure
and morally at fault and cause society's problems.

One
might also look at the famous story "The Necklace" from a Marxist/Economic point of
view.  What is Mathilde's economic situation?  What chance for economic success does she
have?  If she were not poor to begin with, wouldn't she have been aware of the
possibility that the necklace was only costume jewelry, rather than genuine?  What are
the physical costs of poverty?

Numerous literary theories
exist, of course.  For a student, they enable one to do literary criticism from various
points of view and perspectives.