There are so many varieties available, it can be confusing to ID them. Some varieties look alike, but one may be smaller overall with smaller leaves, with a different varietal name, so that needs considering too. Mickfield hostas is a good site, has listings with description and images for loads of varieties, you might find it useful, if you've got plenty of time!

Thanks Bamboo. When I've got "plenty of time" I'll have a look. I know, I have some that in a photo look the same but the size of leaf is totally different e.g. August Moon and Sum and Substance.

Thats what is good about Mickfield, they give good descriptions, general information and pages of images.