What is the difference between the perfect and imperfect tense?

Both the tenses are PAST TENSE. The key difference is what they each mean. Imperfect tense= unfinished action or interrupted action, perfect tense= completed action in the past. (hence the IMPERFECT- not a perfectly finished action if it helps to remember)E.G. j'ai joué= I playEDje jouais= I WAS playINGYou will have to memorise the endings for each formation, and remember the variations, for example être/ avoir verbs in the perfect tense, agreements with être, and the endings in the imperfect.