Cliqz is just a German Mozilla Firefox fork, based on release branch source; they follow upstream development with religious dedication and are keen on removing older versions from the web, for security reasons; yet their notion of privacy/security as implemented in their product can attract lots of criticism; infamous was the Cliqz test pilot experiment pushed in Germany in 2017 by Mozilla to several unsuspected Firefox users:
https://www.zdnet.com/article/firefox-tests-cliqz-engine-which-slurps-user-browsing-data/
As you can imagine, latest (and only one offered) version is Quantum based, excluding any Vista compatibility ; Vista/XP are not supported since 2017, as per their statement:
https://cliqz.com/en/support/support-ende-windows-xp-und-vista
Use Fx ESR 52.9.0 with the "Cliqz extension for Firefox" ? Thanks, but NO thanks...
As for lawlietfox, it's just as it is described in the SF link:
... So the developer (I think he's Chinese) has implemented basically PGO on top of vanilla Firefox, where:
PGO = Profile Guided Optimization (more here )
... All in all, nothing really exciting about either lawlietfox or Cliqz browsers, at least for the Vista community...