Given the equation:
$$ 2x^2 - 8x + 6 = 0 $$
and the expression:
Quantity A: $$ x^2 - 4 $$
Quantity B: $$ 2 $$
Solve the quadratic equation to find the values of $x$, and then determine the values of Quantity A based on those solutions. What is the relationship between Quantity A and Quantity B?