With leaf mold, you are encouraging fungal action to break down the leaves into humus, molds like damp, dark conditions to thrive best. It doesn't necessarily break down faster compared to making compost.
Leaf mold is similar to peat moss, doesn't have much if any NPK value itself, is mostly spongy carbon fibers that have good water retention properties and helps hold nutrients present in the soil.
Compost is similar to leaf mold but since it is made from multiple sources of browns and greens, it has a higher nutrient content than leaf mold.
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