From my observations for the International 3:
Asian/Chinese DOTA = Farm race... they test to see if they can win early and if they can't in 15min to 20min they will just farm. Farm, Defend, Farm, Defend, Farm till they have a fat carry which usually takes about 40+ minutes... most of the time they have a 4 protect 1... they may have 2 carries so if you shut down one they still have the other carry so the carry that got shut down acts as a diverson while the main one becomes fat.
USA DOTA = gank, gank, gank and go straight for the fountain (mostly focusing on one tower lane) and try to end quick. Take risks that either will win or fail.
Navi DOTA = Mostly mid game and will mind F$%K or troll the opponent if they fall behind.
Alliance DOTA = goes for early or mid game end depending on the opponents draft. For example when Navi picked Tide Hunter, they waited till someone on their team had a BKB (most of their team members were building BKBs) to negate Ravage to before participating in team fights.
Basically the team that makes the least mistakes and adapt to counter their opponents wins the tournament. I think it is so close for the top 8 teams that one mis-click/mistake can determine the winner.