Haskell: Where vs. Let

Question

I am new to Haskell and I am very confused by Where vs. Let. They both seem to provide a similar purpose. I have read a few comparisons bet

Answer 1

I found this example from LYHFGG helpful:

ghci> 4 * (let a = 9 in a + 1) + 2  
42  

let is an expression so you can put a let anywhere(!) where expressions can go.

In other words, in the example above it is not possible to use where to simply replace let (without perhaps using some more verbose case expression combined with where).