The way it works was that in 1891, when Carl Elsner first created the swiss army knife, the swiss government (not wanting to produce civil unrest) decided that each company, Victorinox from the German-speaking region, and Wenger from the French-speaking region would each produce 50,000 knives per year exclusively for the Swiss military. Therefore, Victorinox is the "original" SAK, and Wenger was the "genuine" SAK, as Victorinox was created first.
Both companies are now under the same umbrella, since Wenger became financially unstable. Personally, I've always preferred the 'Victorinox' branded cutlery and multi-tools. Other users, simply like the price-point and features on the Wenger knives. The Wenger-branded blades seem more readily available in 'blister-paks' at some outdoor stores, while the Vics counter-top display boxes are featured at military surplus outlets, and stores with dedicated knife sections. It mostly likely depends on a retailer's jobber, and the 'wholesale' lot price.