The Project Underground (aluminum) was the forerunner to the Homegrown. From former Schwinn engineer Rich Adams:
Control Tech manufactured all 300 or so of the original red and black Project Underground bikes. All these bikes were kitted and shipped from the Boulder Test Center by members of the product team.
Project Colorado refers to serial number one of that bike that was presented to the governor of Colorado to showcase all the bike companies that contribute to the Colorado economy....Because of that single bike, people often refer to the whole series as "Project Colorado" when in fact, from it's inception, it was always referred to internally as "Project Underground". The carbon bike that followed of the same name was really just another chapter of the same series of limited edition bikes and frames sold through specific channels (like employee only at shops) and artfully crafted with the emphasis on passion and pushing boundaries for the brand. The bike in the poster "Life's Little Pleasures" is my personal bike - which I still have - and is serial number 2.
The only functional difference between the Project Underground and the 1995 Homegrown was the switch from CNC-machined dropouts with integrated derailleur hanger to forged dropouts with a replaceable derailleur hanger.
Images and quote courtesy Chris Holmes:
The Project Colorado was a Project Underground kitted with a bunch of Colorado-based companies' parts, presented to then-Colorado Governor Roy Romer to show him the importance of the bike industry to the state.
As of 2008, the Project Colorado shown in the images below was displayed at Pacific Cycle's headquarters.