I’m trying to follow the terminology introduced in the Royal Society Report on the future of computing[i] as I think and talk to others about computing in school. Here’s the summary to save you digging through the report:
Computing The broad subject area; roughly equivalent to what is called ICT in schools and IT in industry, as the term is generally used.
ICT The school subject defined in the current National Curriculum.
Computer Science The rigorous academic discipline, encompassing programming languages, data structures, algorithms, etc.
Information Technology The use of computers, in industry, commerce, the arts and elsewhere, including aspects of IT systems architecture, human factors, project management, etc. (Note that this is narrower than the use in industry, which generally encompasses Computer Science as well.)
Digital literacy The general ability to use computers. This will be written in lower case to emphasize that it is a set of skills rather than a subject in its own right.
See also this CAS document which follows the same definitions but adds TEL for ‘Technology Enhanced Learning’ across the curriculum: http://www.computingatschool.org.uk/data/uploads/Curriculum%20Framework%20for%20CS%20and%20IT.pdf