Yes there are, and there are some with superior taste, but that's all I know. Here is a U of FL bulletin with everything you want to know about Loquats.

Here is a link that might be useful: Loquats

Yes, there are different loquat cultivars. The ones that are commonly found for sale usually have small sour fruit. Those are used more as ornamentals. However, there are some wonderful varieties that make a delicious, sweet fruit. These will be propagated by airlayers or grafting. A couple of loquat varieties are 'Wolfe' and 'Oliver'.

Christine

Hi
I think if you start into tropical fruit The best advice is to attend a meeting of one of the clubs or better yet a sale. They allow you to taste many varieties cultivars and will have that cultivar available with all kinds of advice on how best to grow it.
There are DOZENS of cultivars of almost any fruit tree you can name . Not only vary in taste but in growth habit disease resistance production levels and last the variety that grows best in your area.
You will spend years growing any type of tree so why not grow the type that you like best?? gary

Most nurseries sell loquat trees grown from seedlings. Every source I've read says that loquats should be grafted if grown for fruit and not just landscaping. I've found only two Florida nurseries that sell grafted loquats - Excalibur Rare Fruit (Lake Worth) and Jene's Tropicals (St Pete). An ebay nursery in California sells grafted loquats for $108 (yikes!). Some cultivars I've seen in Floria are Oliver, Champagne, Gold Nugget. Loquats are in season now (April). I've stopped and tasted loquats all over South Florida - only a few have been large and sweet enough to be desirable as fruit. People with European backgrounds know loquats as nespoli, loquats are much more popular in the Mediterranean.