A transcendental number is a number which isn't a root of any polynomial with integer coefficients. It's therefore not an algebraic number (of any degree).
All transcendental numbers are irrational but the converse is not true. For example, [itex]\sqrt 2[/itex] is irrational but is a solution of [itex]x^2 = 2[/itex].
e and pi certainly are the roots of 'some kinds of equation', just not any polynomial over Q. They are roots if [itex]x^2-(e+\pi)x+e\pi[/itex], for instance.