Use 'as many as' when comparing to show two things are equal in number. She caught as many fish as I did.
Pro Tip 2/3
Positive Emphasis
Stress abundance or sufficiency when expressing there are enough resources or quantities. There are as many apples in the basket as we need for the pie.
Pro Tip 3/3
Expressing Desire
Convey what you or someone else wishes or prefers in terms of quantity. Take as many cookies as you like from the jar.