Where a recipe lives. No date, no end — a shelf is still there next year.
A meal you're cooking on a day, for a number of people. It borrows recipes from your shelves, scales them, and finishes when it's cooked.
Keeps recipes. Has a name and a count. Never ends, never scales anything, never touches your shopping list. A recipe can sit on several.
Plans a meal. Has a date and a headcount, so it can scale servings, order the prep and build one list. Removing a recipe from it doesn't remove it from any shelf.