Thesis and Dissertations are almost use interchangeably in academic world and cause a common confusion as they are synonyms. Thesis and dissertations are similar in the way they are structured but that does not make the two the same thing. Many people debate over the idea that what difference would it make to understand the internalizes when you have to compose the same structure! That is a very naive and a bit careless approach when you are conducting research for you masters or PhD degree and you are unaware of the main difference.
Moving on, the main difference is that a thesis is usually referred to a masters final project while a dissertation is prepared for a doctoral degree; hence the words doctoral dissertation are often heard together. In a thesis, you are supposed and expected to conduct a research about what you have learned through your program but in a dissertation, you have to conduct some research that could result in some actual difference in the research world.
A thesis explains your methods and approach to others researches and in what ways you present your discoveries in their researches. In a dissertation, you work from scratch and the previous researches serve only to help you build your own hypothesis or come up with an argument about how the inefficiency of any previously conducted theory.
Another way in which a master’s thesis and a doctoral dissertation differ is the length. A thesis is supposed to be over a 100 pages but a dissertation has no bounds unless one imposed by the institute or the university.