Aw where was I in this debate? Need to check the Sports forum more.
I can't add too much to what's already been said of course. The difference between League and Union, aside from the obvious ones, is that often League has more breakaway runs, (less men to beat on the field,) but is also a more stop-start kind of game. Union can be a little more flowing but often isn't.
I haven't really got caught up in the north-vs-south hemisphere stuff, I'll just say that however they differ when two teams from different hemispheres play it's always interesting to see their tactics work against each other and either way the result always comes down to skill. I suppose the stink come from people who didn't like England's play style a couple of years ago which involved milking penalties for their near flawless first-five, (or flyhalf,) which many people said was ruining the game - but hey, it was a tactic that won them the World Cup.
The NRL is always a good competition to follow for League although all the player scandals, player trading or pay-cap breachings get tiresome. Generally though the teams are very even and at the end of the season you'll find 8-plus teams in the running for playoff spots which keeps things exciting.
A good way to get into rugby and get the feel of the game is to watch the Rugby Sevens, (which is on right now.) Seven men a side, ten minutes a half, fast and exciting play with rules similar to Union. Of course here it seems an excuse to put on a costume and drink yourself stupid, if you ask anyone what the result of the Sevens was they'd just probably laugh at you.