1. Cows provide us with milk.
2. Cows provide milk to us.
(Ae both the same?)
3. A cow can make about 12 kilograms of waste in a day.
4. A cow can make about 12 kilograms of waste within a day.
(What is the difference between #3 and #4? The use of 'in' and 'within')
1 and 2 mean the same thing, yes.
3 and 4 mean the same thing, but I don't think I've heard phrasing like in #4 before. #3 is the common phrasing.