Green toys refer to the fact that they are rechargeable and/or recyclable like glass, wood or metal toys. Being better for the environment is honestly up for debate. Yes, they don't use batteries which is wonderful (and really saves a lot of money) but in order for toys to be totally really green, you would have to look in to how they are manufactured (if it is in a way that has minimal impact on the environment) and then how you would dispose of it. If you're just going to throw it in the trash when it breaks down, well then that's not a very green toy in the end. Glass, wood and metal toys can be recycled and toys with motors should be taken to your local hazardous waste drop off and that way they can be properly taken apart and disposed of (a process that should be completely anonymous).
I like my rechargeable toys, I have a couple from LELO who offers a great warranty and quality guarantee. The charge lasts long and their vibes are strong enough to me. More than anything, rechargeable toys are convenient to use. By reading some reviews, you can find out which brands get the general consensus that they are strong and worth the money. Whether they are worth the money is up to you to decide. I think they are worth the money as long as they are good quality, have varying uses and functions and if they have a good warranty too back them up. Of course that refers to rechargeable toys, glass, metal and wood toys obviously don't use any electricity at all and probably are a bit more "green".
I hope that helps a bit!