Here's an example of a Mazda MX5 front upright (spindle, knuckle - depending where you live) fitted with a Mazda RX7 hub. The hub is bigger and stronger and five stud instead of four. The MX5 stub axle is a smaller diameter - hence the tubular bush. The RX7 hub is taller - hence the MX5 upright has been turned down a few mm at the base of the axle to keep the standard offset.
cut and paste this link to see a picture :
http://forum.britishv8.org/read.php?7,28901
cheers
Ross