Meiwa kumquats are more round in shape and are often referred to as "sweet kumquats". 

The Meiwa or Large Round Kumquat (Fortunella.crassifolia) is grown extensively in China. In Japan, it is also called the ninpo or neiha kinkan. It was introduced into the United States from Japan in 1910, but is still somewhat rare here. Meiwa kumquats are more round in shape and are often referred to as "sweet kumquats". They have few seeds and are best eaten whole. While they are very good to eat, it is not recommended that you use them for cooking or for marmalade as they lack the tartness of the Nagami kumquats. The Meiwa kumquats are not normally available commercially. However, we have had some requests for them in the last few years.