Both Snapchat Lens and Facebook AR provide a lot of control during the build process - they each even come with a code editor that lets you build more specific/detailed interaction and animation. Both Studio's are structured quite similarly.
Snapchat has the advantage of coming with a whole heap of templates (and the detect face feature) which significantly speeds up the process when testing and getting familiar with the software features, though I don't honestly know how much they would speed up someone who was familiar with either piece of software.
Facebook AR effects are limited to 1.6mb, while Snapchat limit to 2mb. Neither of these formats seem designed to do any real heavy content or interaction.
Facebook AR provides publishers with links that can be shared anywhere, and posts made on Facebook can have Camera Effects added to them specifically.
Snapchat has links too, but also leverages sharing via snapchat. Anytime a user receives a snap that uses a lens, the receiver has the option to use the lens by swiping up.
In addition, each Snap lens comes with a unique QR code that snapchat can scan to provide access to the effect, enabling some degree of print marketing as well.
All in all they are remarkably similar. I wouldn't say that either kit was significantly better than the other - I would expect the needs of the client/content to drive the choice most of the time here.