In the context of production, how do diminishing marginal returns differ from returns to scale?

Diminishing marginal returns happen when adding more of one input, like labor, leads to smaller increases in output after a certain point. For example, if a factory hires more workers to produce toys, initially, production might rise quickly, but eventually, each new worker adds less and less to total output because they might get in each other's way or run out of machines to use. In contrast, returns to scale refer to how output changes when all inputs are increased together, like doubling all workers and machines. If a factory doubles its inputs and its output also doubles, it has constant returns to scale. However, if output increases more than double, it has increasing returns to scale, and if it increases less than double, it has decreasing returns to scale.