Pairs often confused
puisque or parce que in French?
Parce que TEACHES the cause to the reader; puisque RECALLS it, because they already know it.
Why
Puisque leans on a shared fact to draw a conclusion: it is an argument, not information. Writing "puisqu'il pleut" to someone who does not know the weather rings false. In a letter, puisque picks up what the addressee wrote, which is what makes it useful at B1.
puisque
Puisque vous proposez un report, je choisis la date du 12.
Since you are offering a postponement, I choose the 12th.
parce que
Je n'ai pas pu venir parce que mon train a été supprimé.
I could not come because my train was cancelled.