Or to put it another way.
The main difference between the fluid weights is that the thicker diff fluid increases the ability of the gears to “lock up". Thus, helping to give you an equal amount of power to both tires. Even if one tire is spinning in the air and the other is on the ground, the tire on the ground will recieve more power with the thicker oil than if the diff had a thinner oil.

In saying that with thinner oil on a tight track would more suit a novice driver as power is transfered more to the tyre with the least grip (usually the inside tyre because of the outside tyre being "loaded up" with the weight transfer) this can harm acceleration but makes the car easier to control. (as Rolland said less chance of both wheels spinning and losing control) but for an experienced driver, a thicker oil will provide less inside wheel spin and more evenly distributed power, thus quicker acceleration, but more chance a spin out.