Green hosting is the same thing as normal hosting, but with more marketing paint in it. "Green" is just a modern buzzword, used by marketers to make you pay more for something that isn't worth more.
Like: Where their power comes from, their cooling system makeup, cabling, hardware, and more.
and in most cases it is true or they would get slapped with false advertising lawsuits in no time.
Some Green Hosting companies provides 5400 RPM disks which are quite slow. Just make sure that they are using 7200 RPM disks.
So, doing anything that is environmentally positive can be a reason to call yourself "green", which is exactly what is happening. Almost invariably, there's no real procedure or policy that shows real effort, instead carbon offsetting schemes and the like are used. Basically the host pays a relative small fee, and it return it gets to call itself "green".
I've seen countless hosts take people's money, disappear, and then go at it again. And they weren't sued, because it's not worth the effort to do so. So, while the risk of getting sued is real, it's not something to get overly worried about, especially when your average customer is typically thousands of miles away.
Green hosting is the same thing as normal hosting, but with more marketing paint in it. "Green" is just a modern buzzword, used by marketers to make you pay more for something that isn't worth more.