Watch the videos:
The cleaning kits are about the same price. Looks like the Green Filter video tells you to use a lot less oil than the K&N. It also mentions the Green Filter oil is synthetic. Somebody here had a K&N kit, I looked and it does not say what the oil is.
I do not think the cleaner makes any difference, I have used Simple Green on another K&N.
Probably does not make any difference but I $12 or $13 bucks I would buy the Green Filter kit when time comes.