You can read the variety data on the UCR CCPP website here. They recently updated the information sheets so it might not have as much of the older data.
https://citrusvariety.ucr.edu/citrus-varieties/alphabetical-orderI grow both of them, the Kiyomi is a large fruit, thick skin so no critters will eat through the fruit. The taste is good, very juicy, once in a while it has seeds, mostly seedless. Very reliable producer, fruits hang in cluster, very heavy but the branches also will be thicker so it can handle the weight of the hanging fruits. Tree grows vigorously and a grafted branch can hold many large fruits in 2 years. Kiyomi is one of the parents of Shiranui (sumo) so it might be a good one to use. The other parent fruit is the Ponkan, I like the taste of Ponkan fruit better than the Kiyomi.
The Fina Clementine I grow have very good taste, I like it better than Kiyomi. The Clementine has thin skin, easy peel, normal number of seeds per fruit (4-7), flesh texture is a little different from other mandarins, so I like it. I also notice that the seeds are located in each fruit sack in the middle (like floating), not near the center of the fruit like most citrus. Seeds are also shaped like a thin/flat ellipsoid. Fruit is much smaller(70g) than Kiyomi(340g), shape if very round/spheroid. The tree/branches are thin, growth is slow.
I don't cross any of my citrus, just eat the fruits and always searching for the best tasting.