Both eyeshadows are about the same size.
The Chanel shadow has a dense, moussey texture that dries to a powder finish. It can be applied sheer or more heavily for a more opaque look. It also comes with a small synthetic brush to apply it with and it worked fairly well in my experience. The Armani eyeshadow is very similar to the L'Oreal pressed eyeshadows I reviewed previously: the intensity and colour payoff are like a loose eyeshadow, but it's definitely pressed. Both of them wore really well: the Armani lasted all day without creasing over Urban Decay Primer Potion, while the Chanel lasted all day on its own without creasing.
Left: Chanel. Right: Armani. Both are swatched on bare skin.
This picture shows the colour more accurately. Chanel on the left, Armani on the right.
The colours appear quite similar when they're swatched on the back of my hand, with the Chanel appearing sheerer than the Armani. The colour of the Chanel could be built up so it actually appears more like the Armani, while the Armani was a rich, opaque colour straight off the bat. In real life on my eye, I found the Chanel was a pinkier purple, while the Armani was bluer. I think the Chanel was a little more sparkly, too. So they look similar, but they're definitely different.
Chanel. It's a little more pink and I was able to apply just a wash of colour.
Armani. It's a bluer and darker purple.
Which do I like better? Hmm. That's tough. I think I'm going to have to say the Chanel. I like the mousse texture and that I can apply it as lightly or as heavily as I want. I also appreciate the brush, which makes application really easy. Also, since it's not a powder, fallout isn't even an issue. They're both really lovely, though, and I don't regret either purchase. However, I still don't think I could pay full retail price for them, so even if there was an awesome green in either brand, I'd have to head online to get it and it would have to be a big discount.