Both methods will produce hypertrophy, but lower reps are more geared towards strength while higher reps are better for size. So for strength do no more than 5 reps, lift fast and use heavy weight. For size go with higher reps(8-18) with a slower controlled tempo for 3-4 sets and total about 40 reps per.
For definition - it's all diet. But there are also Tabata, HIIT and GXP. Do a search. They cut fat really well.
This is a basic breakdown. I would recommend not going all out with those last reps i.e. don't go to failure. That way you can train every muscle group at least 2x/week easily. Otherwise you'll recover too long and the soreness doesn't make life easier either.
People will disagree with me on this one but in my experience if you want to be big AND strong then get big first - it's just better for the ego.
Just my two ce...err nickels
