Biofinity (3-pack) have three lenses in each package. Biofinity (6-pack) have six lenses in each box.
The main difference is how long each box lasts in total. Biofinity (3 lenses) lasts up to three months and Biofinity (6 lenses) lasts up to six months if one lens from the box is used every 30 days. Biofinity (3 lenses) are perfect for more infrequent contact lens wearers or those who wish to spend less on one order. The price per lens is slightly less when you buy Biofinity (6 lenses).