I have no idea what a 2040 is...?
A 2040 would be an investment that would be low-risk, low-reward. You're not going to make a ton of money on it -- but you'll never lose money. It's a safe bet. Say you put in 5,000 dollars into a 2040 fund through someone say like Edward Jones, you might earn 5% on that a year. So, 250 bucks. Well, 250 bucks a year over 30 years or so ends up being a nice little reward at the end of the tunnel. You'll gain more than that though -- I'm just using an example to help you out.
A 2010/2020 investment would be putting in something that'd be high-risk, high-reward. The year is basically when you'd "take out" your money. You can lose money here, but you can also make a killing. I haven't set up any investments yet because I'm paying down my debt while I'm in school (I'm fortunate) and recently was diagnosed with a kidney disease so I have some bills to pay -- but investing right now in the early 20's (before 25) will net you hundreds of thousands, if not millions if you just play things smart.
If you ever need any advice in this area or want to talk about stuff like this, I'd like to think I have an inkling or two to share.
I am certainly no financial advisor, but a few points:
First off, I've never heard someone refer to an investment as "a 2040." Rather, I've heard of (and own, incidentally) retirement accounts that are named after the target year when you'd be retiring.
Second, your assessment of risk vs. time-frame is backwards. When you have an investment targeted for 30 years later, that can be much higher risk than something where you expect to use the money in 5 years. In the short term a high-risk investment is pretty much as likely to lose money as gain, but over the long term the ups and downs will average out to a net gain. So when you have enough time to wait out the downs you go for higher potential rewards, but if you aren't planning to wait as long then you go for the sure thing with a smaller reward.
Incidentally, this why it's a good idea to start your retirement account almost entirely stocks and gradually shift toward safer investments over time (retirement mutual funds do this automatically.)
Third, if you are wanting a super safe investment, who the fuck would want to tie up their money for 30 years for only a 5% return? Get a savings account. While some banks will offer you piddling returns, ING was offering 5% on savings accounts up until the markets started crashing this fall.