JUDDD is "Johnsons Up Day Down Day Diet- Also known as alternate day fasting- you fast (consume fewer than 500cals) every other day.
5:2 you fast 2 days out of 7.
DODO I have no idea!
Some people, especially those on JUDDD, fast for 24hrs- e.g 2pm one day to 2pm the other, that way they eat everyday. It works for some people and works best on JUDDD rather than 5:2. 5:2 works best on a 36hr fast e.g fasting from 10pm on a feast day to 8am on your next feast day, consuming only 500cals in between. I hope this helps?