std::array: size and max_size returns same number thought the element in array are less

As we can see from the below code that the maximum element in the array are the same as that of size. I was expecting the size will return me the 2 elements only.

#include <array>
#include <iostream>

enum class x
{
    a = 1,
    b = 2,
    c = 3
};

int main()
{ 
    std::array<x, 3> nums {x::a, x::b};

    std::cout << "nums contains " << nums.size() << " elements.\n";
    std::cout << "max nums contains " << nums.max_size() << " elements.\n";
}

Result:

nums contains 3 elements.
max nums contains 3 elements.