Answer:
String: Once we create a String Object we can't perfrom any changes
in the existing object. If we try to perfrom any changes with
those changes a new object will be created. This non-changeable
nature is called Immutability of String object.
StringBuffer: Once we create a StringBuffer object, we can perform
any type of changes in the existing object. This changeable nature
of StringBuffer object is known as mutability of StringBuffer.
