I'm not entirely sure each variety has an equivalent name in English, but 香蕉 looks like a Cavendish banana (the long yellow bananas). Very short, sweet bananas are called "Lady Fingers". I think 粉蕉 is the closest, judging from the pictures. They're not so good to cook with (they turn grey), so it's better to eat them fresh. "Lady Fingers" can mean a number of different species, depending on the country. 大蕉 is a plantain; we consider this different from bananas and treat it more like a sweet potato when we cook it. 皇帝蕉 I'm not sure about. Perhaps "Goldfinger" is what we would call it. Anyway, I hope that helps.

Check a botanical dictionary.