Hey OUTLAW,
if you read all what is written here and here (both already linked by @suprak above) it’s easy to understand:
Journeyman X-50 is an entire machine with 48″×32″ workarea with 50 mm rails on X axis, while the upgrades are one to upgrade your existing Wookworker X-35 (32″×32″ workarea) to a Woodworker X-50 (still 32″×32″ workarea, but with 50 mm rails on X axis then) and the other is to upgrade your Woodworker X-35 (32″×32″ workarea) to Journeyman X-50 (48″×32″ workarea).