Although the thesis and dissertation are most times thought to be the same in some universities, however, there are some differences between the two. A thesis is a research paper submitted after your research work at the end of your master's degree. It has to be new and original since you are expected to conduct a research work about a subject matter.
In contrast, a dissertation is a research paper written by students at the end of their doctoral degree or Ph.D. program. When writing a dissertation, a student is expected to go through the already existing literature. After this stage, such an individual will need to combine and reproduce all the information to give new research work.
Also, hypotheses are included when writing a thesis. In the case of a dissertation, your final conclusion about what you have read and discovered should be included too. Invariably, while a dissertation is simply the analysis and reproduction of the already existing literature, a thesis is adding to the already existing literature.