Pitaya is just an alternate spelling of the more common pitahaya which is most commonly called dragon fruit (also strawberry pear).
The foodlywise website about dragon fruit explains health benefits of dragon fruit, how to grow dragon fruit and history of dragon fruit.
http://dragon.fruit.pitaya.fruit.foodlywise.com/
There is not difference other than the name between pitaya and pitahaya or dragon fruit.
pitaya
Dragon fruit is just a common name for pitaya which is also called pitahaya or strawberry pear. There is no difference between the plant itself. There are just several names for the same plants.
The scientific name would be Selenicereus megalanthus.
Different cultivars of pitaya are red- or yellow-skinned; the internal part may be white or red.
cacti bear edible fruit such as the prickly pear and hylocereus which produces dragon fruit or pitaya.
Sinaloa comes from the Cahita language, a Native American language found in northwestern Mexico. It is a composition of two words: "Sina-" name of the pitaya or dragon fruit, and "-lobola", meaning round.Hence Sinaloa means "round dragon fruit" or "round pitaya".
Some Mexican fruits starting with 'P' would include:Platano (banana)Piña (pineapple)PapayaPera (pear)Pistacho (pistachio)Pomelo (grapefruit)Pitaya
Dragon fruit can be called Hylocereus cacti, pitaya, pitahaya, fire dragon fruit, dragon pearl fruit, green dragon, or strawberry pear.
The cost of pitaya, or dragon fruit, can vary widely depending on factors such as location, season, and whether it’s organic or conventional. On average, prices range from $5 to $10 per pound in the U.S., but they can be higher in areas where they're less commonly grown. In some markets, individual fruits may be sold for about $5 to $7 each. Always check local grocery stores or farmers' markets for the most accurate pricing.
Dragon Fruit (Pitaya or Pitahaya) can be planted at any time. Spring and Fall are suggested as the best time of year, but other months work, also.
By consuming 100g almonds we will get 705 mg of potassium, banana, apricot, avocado, pitaya, grapes, dates are some other good sources for potassium.
You can buy it online and from some plant nurseries.