User blog:Planterobloon/How do you compare huge numbers to each other?

I know this is a total noob question, but once a number is so big power towers are useless, how do you tell how big a number is compared to other numbers? I know if they're in the same notation it's pretty easy, but if I've got 2^^^4 and I want it in Hyper-E notation (which I'm more comfortable with), how do I do that?