Interface :

IList.CopyTo 

class myClass:IList{
}

Implicit Implementation :

class myClass:IList{
public void CopyTo(Array array, int index)
{
    throw new NotImplementedException();
}

Explicit Implementation :

class myClass:IList{
void ICollection.CopyTo(Array array, int index)
{
    throw new NotImplementedException();
}


}

Invoke :

myclass.CopyTo //invalid with explicit
((IList)myClass).CopyTo //valid with explicit.

Explicit Only be accessed when the instance is casted to interface type .
implicit can be accessed by class type(implemented interface) and interface type .