Google.com will probably give you better information, but both have been recommended as the better anesthesia options. I believe that isoflurane keeps them in a lighter sleep and is much easier to awake the dog, but both are good.
Belle had her dental done with iso and I was shocked at how awake she was 3 hours later. I am not sure if that is good to keep them resting but she was fully awake and ready to attack the dog's next door as soon as she got home. I had to separate her from my dogs and keep her calm.
Linda, while I was waiting for an appointment later, I went to Google and entered both names and saw what you mean. There is a lot of information, including comparisons, that are not as easy to digest. A Hav breeder, who also works in the medical field, is the one who told me that Isoflurane is the one I should request of my vet, but that is what she (my vet) opts for anyway, so I didn't even need to ask for it.