IQ = An intelligence quotient, or IQ, is a score derived from one of several standardized tests designed to assess human intelligence. The many different kinds of IQ tests use a wide variety of methods. Some tests are visual, some are verbal, some tests only use abstract-reasoning problems, and some tests concentrate on arithmetic, spatial imagery, reading, vocabulary, memory or general knowledge.
Quiz = A quiz is a form of game of the mind in which the players (as individuals or in teams) attempt to answer questions correctly. In some countries, a quiz is also a brief assessment used in education and similar fields to measure growth in knowledge, abilities, and/or skills. Quizzes are usually scored in points and many quizzes are designed to determine a winner from a group of participants - usually the participant with the highest score.