When to use Cast() and Oftype() in Linq

I am aware of two methods of casting types to IEnumerable from an Arraylist in Linq and wondering in which cases to use them?

e.g

IEnumerable<string> someCollection = arrayList.OfType<string>()

or

IEnumerable<string> someCollection = arrayList.Cast<string>()

What is the difference between these two methods and where should I apply each case?