Liberte is ostensibly more lightweight and hardened than Tails, but it hasn't been updated since September of last year, while Tails gets updated about once a month with bug fixes and new features. It implements things like obfsproxy bridge support and stream isolation, which Liberte does not. It uses Tor Browser, which is created with a set of 27 patches against Firefox, along with many changes in the default settings, to protect your anonymity and security, while Liberte uses the default Gnome browser. Overall, there are many reasons to prefer Tails over Liberte.