Arrays.sort() is a method residing in Arrays class. It is used to sort the Array passed to it. It can be integer array, float array, String array, Array of objects etc.
The time complexity for this method is O(nlogn) as it runs quicksort in background
sort() method is best optimized, so if you use this method instead of writing your own, you'll get best results.
Collections.sort() is used to sort an object which extends List interface. ArrayList and LinkedList extend List interface, so we can sort them using Collections.sort.
Collections.sort() has a time complexity of O(nlogn) as it run merge sort in background