I posted an answer to a similar question on BeautyTalk actually~

Guerlain Meteorites ARE super fun! They're super pretty to have sitting on your counter and they do feel super luxe when you use them.

• They last FOREVER. It's just so much product in that tin
• They're terrible for traveling since they tend to crumble if you shake them too much. This was my solution to that that also helps with keeping my makeup bag lighter.
• You can use them as a subtle highlight depending on your skin tone. I use it as a finishing powder mostly (I'm NC 35, medium w/golden undertones)
• You can use build it slightly to create a highlight -- just don't expect Becca Pressed SSP highlight
• They're more shimmery than the Hourglass ALPs. It's not like...glitter glitter but it's definitely noticeable in the sunlight or if you're heavy handed, etc.
• If you're sensitive to fragrance you may want to skip them
• They kind of correlate to skin tone but I'd say that Mythic 01 (in the compact thats $) is pretty universal since it's almost translucent aside from the shimmer. The standard pearls they have, Clair 02, Medium 03 and Dore 04, also come in compact form (which is super cheap looking...what a shame) and they do correspond more to skin tone. I color match best to Medium 03 but I use Clair 02 with a light hand with no issue
• They're really subtle, but because of the shimmer they're not quite as subtle as the Hourglass ALP so you might like that?

Are they entirely different? Not reaaaaally. IMHO, I think it depends on your skin tone and whether you want to embrace the shimmer. For me I decided not to get the Hourglass after trying it since I have Mythic 01, Holiday 2015 Perles, Clair 02 and Blush 00 -- it's just a lot of product to go through and similar enough that I don't neeeeed it.