Very famous question. It may have come in your exams and it may appear in an interview too.
C is a structured programming language.
C++ is an object oriented programming language. In C++ you have got the concept of a class which is a user defined data type. An instance of a class is an object. C++ was built as an extension of C.
C is good for low level programming like building Operating Systems, Device Drivers etc.
C++ is useful for High Level Programming for building complex systems.