Statement of purpose is written and eventually you will determine the thesis statement and done some research. You will state your thesis statement in your introduction and prove your thesis statement with facts in the body of your paper and finally repeat it along with a summary and in your conclusion.
Thesis statement is written to prove with evidence. It should be a product of your serious thinking after having some research. The thesis statement will be the main focus of your total project. It should be the main idea of your paper. Make sure that you have enough research to have a strong argument.
You will never have a thesis without a thesis statement which will tell the reader the importance of the subject matter or main idea and exactly inform the reader what to expect to the rest of the paper. Thesis statement is usually a single sentence that presents an argument to the reader.
To formulate a thesis statement, you should have a problem and then think of a possible argument. After you have an argument, you can now start to search for the sources of information to make sure that you will have enough evidence for your thesis statement.