Since you mentioned studying part-time, what really is the difference between full-time and part-time study in a PhD program?

For example, in Translation Studies, the requirements are: a translated piece of writing from another author (40,000 words), a critical analysis of the translation process (35,000 words) and a professional development program.

In my (very limited) understanding, studying part-time just means you have longer to complete your written works, which are really completed on your own schedule so long as you finish before the end of the course.

Or are there other (say, semester-based) requirements that will be further spaced out during a part-time mode of study?