What's the difference between "inferencing" and "inferring"?

inferencing [ˈɪnfərənsɪŋ] n (Linguistics)

Psycholinguistics the practice of inferring the meaning of an unfamiliar word or expression from the meaning of familiar words occurring with it in a context together with one's knowledge of or beliefs about the world

As distinct from inferring, inferencing is a term with a specialized meaning in the field of linguistics, which is now finding wider application in other areas including artificial intelligence, graphics, high performance computing, control systems, semantic web technologies and several emerging fields as well.

An interesting page from the Open Knowledge Foundation About Inferencing is a good place to start.