I've played rugby for 10 years of my 18 on this planet and have been lifting weights for 3 years and done other fitness training for my sport for thwe last 2 or 3.
Basically, it depends on your position and the fitness components for your game. ALL PLAYERS NEED EXCELLENT ENDURANCE. aside from that factor, position speciffic training can varry greatly....thats why you see very difrent body types on the field.
The front row should concentrate on strength, power and scrumaging skills whilst a centre would concentrate on explosive power, agility, speed and strength.......
Cleans are a must with weights, squats, deads, bench press and lots of sprinting, jogs and most of all just play the game, you will get the fitness from just playing alot.......conditions your body to take hits too......
good luck