The short answer to your question - is the DB twice the bike? - is an unqualified YES.
DB has a high grade 6061 AL frame, the Gen is low grade (heavier) AL.
DB has double-wall rims w/ stainless steel spokes, the Gen does not.
Drivetrain components are a step up on the DB, not huge, but still better.
The cheap disc brakes on the Gen truely suck, they will barely stop the bike, and that's if you're going uphill.
The weights you quoted are probably not accurate, the DB is probably more like 30 lbs, the Gen is probably around 40, but it's still a big difference, and it WILL matter to you later on, even though you're thinking it's not a big deal now.
Ignore the rear suspension on the Gen, it adds weight, you don't need it, and it will be more of a detriment to pedaling efficiency than anything.

To sum up, the DB frame and wheels are something which will last you for a while and make a decent platform for maintaining/upgrading later on - the Gen is a boat anchor that you will tire of quickly, and is essentially a throw-away bike (when components start breaking it's not worth putting any money into).

Hope that helps.

BTW, you will likely get responses that say, buy used from Craigslist, you'll get more bike for your money. This only works if you know how to assess bikes and components for both quality and state of wear/disrepair. You can easily end up with a "high quality" bike with a bunch of worn out components. This doesn't sound like your thing to me based on your post.