frend
there is two forms in polymorphism
1.early or static binding
2.dynamic or late binding
basically binding means interface b/n functoncall n real function.
in function overriding we use the concept of virtual function.
means if we place virtual keyword before function in baseclass(we must write virtual function base class only)it becomes virtual to all the derived classes to it.that means it overrides the base class function
that means it exicutes the function of derived class instead of base class.
in this we write function of same type & arguments. if we pass differently it ignores it.
where as in overloading we use the concept of static binding.that means it is fixed. we may not change. in this the no.of arguments & type
are same,except function name. and it is in the same class.where as in function overriding we write same function definition in different .
i don't know how i can explain u.
but if u want more information please go through the book ASHOK N.KAMADHANE PEARSON PUBLISHERS it is easy in language and very lucid explanation.

thank u
REGARDS,
SUHANA.