Here is an outline of potatoes you can find in Okinawa (in no particular order). The word for potato is imo 芋 in kanji, いも in hiragana. I will upload some images later for easy identification.
jaga-imo じゃがいも: this is plain old potato.
May queen メイクイーン: a popular type of jaga-imo. There are probably several varieties of jaga-imo around, but there are not always specifically labelled.
beni-imo 紅芋: the famous purple Okinawa potato. The skin is white-ish and the flesh purple, it is somewhat sweet. Many people use it to make desserts.
ougon-imo 黄金芋: these are orange sweet potatoes grown in Ikei-jima of Uruma city. These are related to the famous annou-imo 安納芋 in Kyushu on mainland Japan. These potatoes are so naturally sweet and flavorful. Many people use them like “american sweet potatoes.”
satsuma-imo さつまいも: these are yellow sweet potatoes, usually with a reddish skin. They are usually baked or made into candy/sweets. Many people buy these thinking they will be like american sweet potatoes, but they do not cook the same. These are best as yaki-imo (baked potato) and are sold in stores already baked over hot stones in fall and winter. There is even a yaki-imo truck that drives through neighborhoods it is so popular.
murasaki-imo 紫芋: these are the purple species of satsuma-imo. Used similarly as above… baked!
sato-imo 里芋 or taimo 田芋 (taamu ターム or taanmu ターンム in Okinawa language): Taro! Of course it is popular here in Okinawa. It seems some westerners do not know what to do with it, but islanders (and some others) all know how and have many different ways to eat this. Chinnuku ちんぬく is a type of Okinawan taro sold in stores. Popular ways to eat taro: boiled then mashed with a bit of sugar, stews (try a polynesian version with coconut milk and fish), or fried chips.
yama-imo 山芋: this wild mountain yam. It has many uses and is very healthy. That being said, its texture is usually a tad slimy and sticky when it is grated. A popular topping for Japanese soba noodles and also used when making okonomiyaki.You may also see it called naga-imo 長芋.