The LZ4 website has benchmarks that are probably more accurate:
According to them, LZ4 is faster than Snappy. The compression rate is 45% higher while the decompression rate is 26% higher. The compression ratio of LZ4 is also slightly higher than that of snappy.
With that said, it appears that btrfs support for both Snappy and LZ4 has not been merged:
Gentoo Linux's ZFS kernel modules gained support for LZ4 two days ago. Gentoo's GRUB package was updated with support for booting off LZ4 compressed ZFS /boot datasets yesterday. People interested in filesystems that support LZ4 compression could always try ZFS.