When comparing Tails vs PureOS, the Slant community recommends Tails for most people. In the question“What are the best Linux distributions for desktops?” Tails is ranked 18th while PureOS is ranked 56th.
Ranked in these QuestionsQuestion Ranking
Pro Privacy focused
Pro Has TOR built-in
Use the Internet anonymously and circumvent censorship; all connections to the Internet are forced to go through the Tor network.
Pro PureBrowser and TOR
PureBrowser is a modified version of Firefox that comes with security focused plugins. There is also a copy of TOR installed in the OS by default.
Pro You can download and install it, without the need to purchase their laptop
PureOS is available from their site for free for anyone to use, no need to purchase any of their laptops in order to check out the OS which is a tweaked build of the Trisquel distro.
Pro Default install on a free, open source laptop
PureOS is the default OS installed on the Purism Librem laptops.
Con Not for daily use
Tails is a privacy focused Linux distro. The updates that you will receive are only for improving privacy and not for improving user experience.
Con Saved states are not present for security
For security reasons, saved states are not supported in Tails. Files can be stored in a separate, persistent volume which must be accessed with a root password. Personal settings (e.g. -- keyboard layout, window settings, etc.) are not saved persistently across reboots. This can be a hindrance for anyone not using English as their language, or not using a QWERTY keyboard layout.
Con You can't install it to a hard drive
Con Slow internet
Tails uses the TOR network and as a result the internet on your computer will be very slow.