Health Sherpa doesn't try to do the more complex operations that the government site will offer - such as actually applying for insurance coverage.
But it does provide a more streamlined way of searching through the plans, and it is actually up and running.
---
Well that right there explains why they were able to get it up and running so much faster. All they had to do was provide information. They don't have to worry about people actually signing up for anything, nor do they have to worry about ensuring that a user's medical and personal information is accurate, nor do they have to transfer that information to health care providers. If your site is for purely informational purposes, then obviously it's going to be much easier to get going than something that has actual utility.