infusion

As nouns the difference between infusion and input

is that infusion is a product consisting of a liquid which has had other ingredients steeped in it to extract useful qualities while input is the act or process of putting in; infusion.

As a verb input is

to put in; put on.

As nouns the difference between infusion and irrigation

is that infusion is a product consisting of a liquid which has had other ingredients steeped in it to extract useful qualities while irrigation is the act or process of irrigating, or the state of being irrigated; especially, the operation of causing water to flow over lands, for nourishing plants.