Your Browser is OutdatedQ&A for Winchester USA Limited 5.56x45mm NATO 62 Grain Green Tip M855 Full Metal Jacket Boat Tail (FMJBT) Brass Cased Centerfire Rifle Ammunition — 2 Questions & 1 Answers
Good question, wish I could find an answer. It appears to be the same ammo (3060 FPS). It's odd that Winchester is not prominently displayed on this better priced version. I found this on several web pages with additional photos, and none of the box sides had Winchester, just Made in USA. It's probably somewhere on the back. Because this round is on their military contract at the Lake City Army Ammunition Plant, these might be excess military rounds sold at a discount under the white box 'USA' label for contract reasons.
Theory #2 - It's just a pricing/marketing technique to differentiate the same product at different pricing tiers.
Either way, it's a great price for 5.56 ammo!