@seolhwayoon Test and exam are used interchangeably but technically DO have different meanings.
A quiz is a small test. There are generally no more than 20 questions (although they are usually much smaller) and it is the least weighted grade. They generally test you on one section or unit of the course you are taking. These are generally multiple choice or true or false questions.
Tests are larger, anywhere from 20-50 questions on average (although there could be more, depending on your professor) and have a medium weighted grade. These generally make up the bulk of your grade and can either focus on one unit of the subject or be cumulative. These are generally multiple choice, true or false, fill in the blank, or short answer questions.
Exams are generally the largest of the three, ranging from 50-100 questions, and are almost always cumulative. Think mid-terms or final exams. These can have a combination of all kinds of questions, and can even include short essays. They generally comprise a HUGE part of your grade .