All the fine details
#5 (HOT) - Has a larger opening around the wire which has the effect of acting like a slightly hotter plug without actually changing the alloy of the wire. This one is the go-to.
#5 (Standard)- This is what the JW12 engines ship with, it's pretty much right in the middle
#6 - This is the colder plug, about as cold as you would want for off-road. This is for applications where you're at wide open throttle a lot, or if you are running a thin head shim stack with a high nitro content