What's the difference between satisfying and satisfactory?
I'm not a teacher, but I would say that they are examples of the importance of context. If I describe a meal, or a book, or a film as a "satisfying" experience, I'm saying that I was left feeling pleased afterward. I was not left with a feeling that something was missing, but rather, I was satisfied.
Satisfactory, on the other hand, has been shifting in meaning for some time now. The OED offers as one definition of satisfactory, " Sufficient for the needs of the case, adequate." and this illustrates how the meaning is shifting. You will often see "satisfactory" used in contexts that imply an emphasis on the "adequate" definition, just enough, no more than is barely necessary. A child's school report may say that their performance in a certain subject was "satisfactory", and this would imply that they
barely met the requirements. They did not fail, but nor did they excel. The word is used as a technical compliment, but often with very faintly pejorative undertones.
To return to the meal: If a waiter asked me "how was the meal?" and I replied, "satisfying", it is likely that they would be happier than if I replied, "satisfactory". The first one suggests pleasure and praise, the second often suggests mediocrity, in between complaint and compliment.