A thesis proposal is a document submitted to a student's academic advisor, proposing a topic for their thesis or dissertation. The proposal outlines the student's research plan, including their research questions, methodology, and expected outcomes.
A thesis defense, also known as a viva, is an oral examination of a student's thesis or dissertation. During the defense, the student presents and defends their work to a panel of examiners, typically made up of academic experts in the student's field. The defense is an opportunity for the student to demonstrate their understanding of their research topic and to answer questions from the examiners.
In summary, a thesis proposal is a written document submitted in advance of the thesis defense, while the thesis defense is an oral examination of the completed thesis or dissertation.