Effective field goal percentage (eFG%) differential: This should be self-explanatory: the team that shoots more efficiently - their field goal percentage weighted for the extra value of three point shots - gives themselves a better chance to win. Typically, the teams that make it to the Final Four have a large eFG% differential, which means two things: they shoot efficiently while also defending well enough to prevent their opponents from shooting efficiently. Yet it's also important to note how this works for strong defensive teams: even if they're not an elite, their sizable eFG% differential is due to the fact
Turnover rate (tov rate): This one is tricky because it might seem that there's no relationship to how many turnovers a team commits and forces - unlike rebounding (and to a lesser extent, scoring), creating a turnover doesn't necessarily negate an opponents' ability to do so. However, what this does tell us is how well a team controls the ball relative to their opponents given their style of play. And teams that turn the ball over more often than opponents tend to be erratic offensively.
Offensive rebounding rate (oreb%) differential: Offensive rebounding is important because it extends possessions and gives teams a chance at second chance points. A team with a significantly better offensive rebounding differential than their opponents is doing two things though: both getting offensive rebounds and preventing opponents from getting offensive rebounds on the other end. It's therefore an indicator of not only rebounding dominance, but some level of interior prowess.
Free throw rate (ft rate) differential: Free throw rate is the rate at which a team gets to the free throw line relative to their opponents, which is a proxy for understanding how well a team attacks the basket offensively (and to some extent, avoids fouls defensively). This is the least significant of the Four Factors and, not surprisingly, there are a number of very good teams (college and pro) that have a negative free throw rate differential. So in the cases when it is a "strength" for a team, it's a relatively weak strength that is hard to take much from when looking at a matchup.