paging is managing RAM data by pages (nK chunks, called page size),
swapping stores it temporarily on disk if it's not needed right away to extend
physical memory through a technique called
virtual memory management (VM). When the kernel moves data between RAM <-> CPU that is paging, and data moved between RAM <-> DISK is swapping.
[Actually, the memory management is usu. handled but a subprocessor component called the MMU, but for practical purposes, let's just say it's in the CPU package deal.
]
Specific flavors of UNIX use slightly different techniques and tuning. Getting down to the nitty gritty is
kernel tuning, which is one of the Black Arts of UNIX. For Solaris specifics, see Adrian Cockroft's book "Sun Performance and Tuning" (slightly outdated, but is considered the "bible" on Solaris tuning).
-Phrazz
See more here:
Paging (Wiki)