Arrays & Array Methods (map, filter, reduce)

The key differences between map() and forEach(): 1) map() creates and returns a new array with transformed elements while forEach() returns undefined, 2) map() is used for data transformation while forEach() is for side effects, 3) map() preserves array length with one-to-one element mapping, 4) forEach() cannot be chained but map() supports method chaining, 5) map() maintains functional programming principles by not modifying original array, 6) map() creates a new array in memory while forEach() doesn't allocate new memory, 7) map() is preferred for data transformations in functional programming, 8) forEach() is better for performing operations that don't require a new array.