The orbital axis of all the planets in our solar system are roughly parallel (within 10 degrees, Mars is just under 2 degrees off ours), so it would be fair to pick a north pole at the same "end" as ours. http://en.wikipedia.org/wiki/Orbital_inclination
The article you linked to describes the angle of plane of the orbit - the circle it makes around the sun. These vary by only a small amount.
The axial tilt is different. It is basically how far the axis through the poles of a planet is tilted compared to the plane of its orbit. This is what you were thinking of initially - it can very a lot.
