General Discussion is supposed to be where we just talk about various Sims 3 things. Miscellaneous Help is supposed to be where you go if you have a specific issue need help with that doesn't really fall into the category of a specific Expansion Pack and isn't of a technical nature (game/computer mechanics).
The "Share Your Sims 3 Stories and Projects" board is basically the mother board for all stories. The "Miscellaneous Stories" board is a child board, along with the Legacy Stories, Dynasty Stories, Project Stories, and Completed Dynasties. Theoretically, all stories should be able to be categorized on one of the child boards. However, a lot of people post on the main mother board. If I see them, I generally move them to the more appropriate board.
Does this help?