Thesis vs. Dissertation: What's the Difference?

These terms are used inconsistently enough that confusion is genuinely reasonable — the answer depends heavily on which country's academic system you're in.

In the United States

A thesis is typically the culminating research project for a master's degree. A dissertation is the culminating, original-research project for a doctoral (PhD) degree — generally longer, more original in its contribution to the field, and defended before a committee.

In the United Kingdom, Australia, and much of Europe

The terms are often reversed relative to US usage: a "dissertation" frequently refers to an undergraduate or master's-level project, while a "thesis" refers to the doctoral-level work.

What actually differs, regardless of terminology

• Scope of original contribution — doctoral-level work is expected to contribute genuinely new knowledge to the field; master's-level work more often applies or synthesizes existing knowledge.
• Length and depth — doctoral projects are typically substantially longer and more methodologically rigorous.
• Defense process — both are usually defended orally before a committee, though expectations and rigor differ by level.

Why the terminology matters less than the requirements

Whatever your institution calls it, check your specific program's handbook for what's actually expected — required chapters, word count, defense format, and submission timeline vary enormously even within the same country and degree level.