what is the difference between a thesis and a dissertation

This is the written component of a practice-based thesis where the major output is a creative work. The exegesis constitutes at least 20% of the thesis.
At AUT, a thesis is associated with either a Doctoral or a Master’s degree. It is a substantial piece of original research. A dissertation is associated with either a Master’s or a Bachelor’s degree with Honours and may be a smaller piece of research or a critical analysis and evaluation of the literature related to a topic.

The 120 points masters thesis is usually around 35,000-40,000 words including an abstract of about 350 words. It generally follows a BCom (Hons) as part of a 120 point Master of Commerce (MCom).
The 60 points master’s dissertation will be around 20,000 words and expected to follow the Level 9 CUAP guidelines for a master’s dissertation. It is part of a 180 point MCom, which will be available from 2017, subject to CUAP approval.

References:

http://uoa.custhelp.com/app/answers/detail/a_id/10081/~/mcom-difference-between-dissertation-and-thesis
http://www.yourdictionary.com/thesis