I had no clue on the Sharks. I'm pretty sure SBW played for the Roosters at one point, which is pretty much the only reason I recognized the uniform. I only know enough to know that I know basically nothing about the NRL.
Rugby league has fewer players on the field (13 vs 15), is a bit freer in play, and generally everyone's roughly the same body type. You get 6 tackles to score, or you have to turn the ball over. Score values are lower than in union, and the field looks kinda like an old time American Football field with the posts on the goal line rather than at the back of the end zone. After a tackle, you have to drop back 10 yards before making the next tackle unless you were involved (I think, I don't understand the play-the-ball).
Rugby Union has no tackle limit; you can take as many carries as you wish to try and score. You also have more competitive restarts in rugby union than in league, so you have a bit more variety in body type; You have football linemen for the front row of your scrum, basketball centers for lineouts, and then the tiny guy who looks out of place on the team to run from tackle to tackle and get the ball out and moving again. Pretty much if the ball is in bounds, you can fight over it. They're very different games, in the end.