Of course, it is concerning that these differences were not spelled out prominently. LiteSpeed is advertised as "APACHE INTERCHANGEABLE". That implies that it is functionally equivalent, however this is not the case in terms of mod_security. And, of course, security is critical in today's climate.
The biggest question is how secure LiteSpeed is (in terms of mod_security) compared to Apache. Please feel free to explain further, so we can decide whether LiteSpeed is safe to use.