Instead of writing this out again, I'm going to quote and link to my previous answer:
As of 2021, some of the "improvements" that Litespeed has developed
vs. Apache are more theoretical than practical, such as HTTP/3 support
(UDP-only) which is not even widely supported:
https://stackoverflow.com/questions/60701073/any-benchmarks-showing-litespeed-faster-than-nginx-servers/69124776#69124776
https://wordpress.org/support/topic/litespeed-or-apache-for-wordpress/
The more "core" features of Litespeed are their PHP handler LSAPI
(LSPHP) and server-level cache which they call LSCACHE (not to be
confused with the WordPress plugin they also released separately). The
benefit here is that the same vendor is coding all these things, which
means they should work smoothly together and can follow a more
accelerated development timeline, etc.
One of the biggest reasons that people assume Litespeed is "better"
than Apache is because they don't realize Apache already supports
multiple caching methods, but that is simply not advertised well by
most web hosting companies who prefer making money from selling
WordPress cache plugins, etc, or by calling their caching feature
something ridiculous like "ABC HOSTING SUPER CACHE".
The other major reason is because Litespeed has invested considerable
effort into "confusing" WordPress users especially by publishing
dishonest benchmarks showing that Litespeed performance being much
faster than both Apache and even Nginx -- dishonest because, they did
things like disabling FastCGI Cache on the Nginx server to ensure it
performed slower, among who knows what else.
In conclusion, most users should not be using OpenLitespeed in production at this point because it's brand new software and relatively unstable compared to Apache/Nginx.
Litespeed's aggressive marketing team is trying to get the word out, that's all.
And remember that many of the features in Litespeed (premium) are not available in OpenLitespeed... for example you must restart the server after any .htaccess changes. And of course, OLS also does not support open source PHP handlers like PHP-FPM, which is ironic... in fact, they have been actively discouraging users from trying to compile PHP-FPM on OLS servers, rather undermining their alleged "open source" project values.