What’s the difference between jam, jelly, and preserves

I haven't made jam in years and don't know first-hand, but this website suggests it won't scale as the jam won't cook as well. This seems predicated on the idea that your cooking vessel remains the same size but the batch is larger.

From the linked site:

Most jam recipes already call for you to use the widest pot you have, for maximum surface area. This large surface area leads to faster evaporation of water. Fast cooking leads to the freshest tasting, best textured jam.

However, if you double the amount of jam in your pot, you greatly increase the cooking time, because there’s so much more product in the pot that needs to be cooked down. This can lead to rubbery batches, burning and jam that doesn’t set.

This is also supported by another site that claims doubling is difficult "due to inherently uneven heating of home cookware".

Per nico's comment, it sounds like doubling/scaling is possible - perhaps give it a try in cookware appropriate to the doubled batch size.

There is considerable overlap between cupcakes and muffins.

Method

From a technical point of view, muffins are made by the muffin method, making them small quickbreads. In the muffin method, the wet ingredients are combined in one bowl; and the dry ingredients are combined in another bowl. Then the two are quickly incorporated together with minimal mixing to avoid gluten development. This gives muffins a somewhat coarse crumb.

Cupcakes are small cakes, and are made by one of the traditional cake methods such as the creaming method, the reverse creaming method, the genoise method, the chiffon method, and so on. They tend to have a finer crumb than muffins.

Contrast

While no single criterion distinguishes a muffin from a cupcake if you do not adopt the technical definition above, the following trends exist:

• Cupcakes tend to be sweeter than muffins; there are savory muffins such as cornbread
• Cupcakes are often iced or frosted, whereas muffins tend to have no topping, or a simple crumb topping
• Cupcakes usually have a head or top no larger than the body of the cupcake; muffins are often encouraged to overflow their baking cup, so that their top is larger in diameter, giving them somewhat of a mushroom shape
• Cupcakes are almost always, well, cupcake shaped; muffins can be made as just muffin tops
• Cupcakes are almost never crispy or crunchy; muffins are often encouraged to brown and develop texture, especially on the tops