What is the difference between a bachelor's, master's and doctorate?
They are three levels of higher education qualification, distinguished by depth, duration and — most importantly — by what you are expected to do with knowledge rather than how much of it you have.
Bachelor's degree (BA, BSc, BEng). Typically three years in the UK, four in the US and much of Europe. The purpose is to develop a broad, structured grounding in a discipline: you learn what is already known, taught through lectures, seminars and set reading, and are assessed on understanding and application. Most include a final-year project or dissertation as a first taste of independent work. It is the standard entry qualification for graduate employment.
Master's degree (MA, MSc, LLM, MBA). Typically one year full-time in the UK, one to two elsewhere. The shift is toward specialisation and independence. You go deeper into a narrower area, engage with current research literature rather than textbooks, and produce a substantial dissertation. Taught master's are mostly coursework with a dissertation; research master's (MRes, MPhil) are predominantly independent research and often serve as a route into doctoral study.
Doctorate (PhD, DPhil, or professional doctorates such as EdD, DBA, MD in some systems). Typically three to four years full-time in the UK, often longer elsewhere. The defining requirement is an original contribution to knowledge — you must produce findings that did not previously exist, defended in a thesis and usually an oral examination (viva voce). You are no longer being taught; you are supervised while doing research. This is the qualitative break: a bachelor's and master's assess your grasp of a field, a doctorate assesses whether you have extended it.
Levels differ by country. The Bologna Process aligned much of Europe into a three-cycle structure, but entry requirements, funding and titles vary considerably.