LispWorks multiprocessing uses native threads and supports Symmetric Multiprocessing (SMP). The implementation is referred to as "SMP LispWorks" where relevant.
Prior to LispWorks 8.0, some platforms uses a single native thread and implement user level threads. The implementation is referred to as "non-SMP LispWorks" where relevant.
In SMP LispWorks, Lisp processes (as reported by the Lisp function ps) are Operating System threads. These do not necessarily correspond to what system tools show you, for example in Microsoft Windows the Activity monitor shows OS processes, including exactly one for each running LispWorks image.
LispWorks® User Guide and Reference Manual - 01 Dec 2021 19:30:21