As far as I can work out from asking just about anyone I can find and have added most to the wiki here
https://www.ausbonsai.com.au/wiki/index.php?title=Azalea
Satsuki is a late flowering variety, ( i believe it means 5th month) ie May in the northern hemisphere.
Kurume are evergreen azaleas with considerable cold hardiness and were introduced from Japan. Kurume azalea plants thrive in the cooller areas and climates. Smaller shrubs grow small waxy leaves and are considered to be dwarf azalea plants, growing 4 feet tall
Azalea indica is originally found on the Indian / Asian continent in the warmer areas and as such as less cold hardy then the Satsuki or Kurume varieties.
These Azaleas are spring blooming and the foliage is evergreen.
If anyone has more info them please post either here or in the WIKI
Ken