What is the difference between UML and RUP?

The unified modeling languege  is a standardized specification language for object modeling. UML is a general-purpose modeling language that includes a graphical notation used to create an abstract model of a system, referred to as a UML model.

http://en.wikipedia.org/wiki/Unified_Modeling_Language

While RUP is The Rational Unified Process (RUP) is an iterative software development process framework created by the Rational Software Corporation, a division of IBM since 2003.
RUP is not a single concrete prescriptive process, but rather an adaptable process framework, intended to be tailored by the development organizations and software project teams that will select the elements of the process that are appropriate for their needs.

http://en.wikipedia.org/wiki/Rational_Unified_Process