The Definition of Academic Integrity does not vary from institution to institution. What does seem to be inconsistent is how it is enforced.
Academic Integrity can be defined by honest academic work where (1) the ideas and the writing of others are properly cited; (2) students submit their own work for tests and assignments without unauthorized assistance; (3) students do not provide unauthorized assistance to others; and (4) students report their research or accomplishments accurately. http://www.ethicsed.org/programs/integrity-works/ai_definitions.htm