So far I only have the hitachi and I really liked it. Here's what I thought about it: link

Honestly I have tried both and there are two main differences - size and power. The size may be nicer but its nowhere near as strong. Honestly I have a third option that I prefer a hundred fold over both others -the couture inspired by cal ex because its silicone and its small enough to use during sex and its basically like the hitachi on low - definitely enough for 99% of women.
I have a few - the only issue I've found us that with daily use the cord can short out but that's about it. Plus it's a decent price- almost always on sale on Eden

I was wondering the same thing because I've only ever used the hitachi out of the two and reading the reviews it seems the fairy is smaller in size but they pretty much look the same, but do they work differently is what I'm wondering.

Sounds to me like both would be good to have. One for home and one for travel.

The best thing about tge Hitachi is all the attachments you can use with it. Also, if it's too intense for you at it's normal settings you can buy a speed control device that will allow you to dial it down.