Question

How are quadratic equations different from linear equations?

Answer 1

In a linear equation:
-- the highest power of the variable that appears is the first power
-- the equation has one solution at most

In a quadratic equation:
-- the highest power of the variable that appears is the second power
-- the equation has two solutions

Answer 2

Quadratics always have a squared value and linears don't. Quadratics have 2 answers and linears have 1.