Are there differences between this Chromium PPA (https://launchpad.net/~chromium-daily/+archive/stable) and the one in the Universe repository?
Are there reasons to choose one over the other? Since the PPA is maintained by Ubuntu developers I assume it's as safe as anything coming from the Universe repository.
The PPA package is updated to the most recent version (in the upstream stable line) potentially every day (not every day in practice, because the stable line doesn't update every day).
The package in the universe repository is only updated if there's a security issue. Unlike most pacakges, the security updates to the Chromium package bring in fairly recent versions of Chromium, presumably because backporting the security fixes is hard. Still, the universe repository is updated a lot less often, so the PPA gives you a more up-do-date system at the cost of making frequent downloads and system changes (it's less stable, in Debian terms).
The main difference is the stable PPA is a straight backport of, usually, the latest packaging and update from the stable channel. This PPA is provided without any testing. The Ubuntu archive version gets updated once there is a new security update that has been run through some tests and if there are no major regressions found in the update. The version in the archive might be using older packaging. The PPA might also come with some extra translations for the Desktop files.
