[temp.type]

Two template-ids refer to the same class, function, or variable if

(1.1)
their template-names, operator-function-ids, or literal-operator-ids refer to the same template and
(1.2)
their corresponding type template-arguments are the same type and
(1.3)
their corresponding non-type template arguments of integral or enumeration type have identical values and
(1.4)
their corresponding non-type template-arguments of pointer type refer to the same object or function or are both the null pointer value and
(1.5)
their corresponding non-type template-arguments of pointer-to-member type refer to the same class member or are both the null member pointer value and
(1.6)
their corresponding non-type template-arguments of reference type refer to the same object or function and
(1.7)
their corresponding template template-arguments refer to the same template.

template<class E, int size> class buffer { /* ... */ };
buffer<char,2*512> x;
buffer<char,1024> y;

declares x and y to be of the same type, and

template<class T, void(*err_fct)()> class list { /* ... */ };
list<int,&error_handler1> x1;
list<int,&error_handler2> x2;
list<int,&error_handler2> x3;
list<char,&error_handler2> x4;

declares x2 and x3 to be of the same type.

Their type differs from the types of x1 and x4.

template<class T> struct X { };
template<class> struct Y { };
template<class T> using Z = Y<T>;
X<Y<int> > y;
X<Z<int> > z;

declares y and z to be of the same type.

— end example

]

17 Templates [temp]

17.4 Type equivalence [temp.type]