Theyre similar plans. You pay your money and you get all of the goodness both companies can give you for their respective software for a year or three. But one, Software Assurance, has been something of a flop, while Red Hats new licensing plan has taken it from being merely the leading Linux company to being a leading ($3.2 billion market cap) IT company.
Why? If you look at them closely, it looks like you get more out of Software Assurance (SA). I mean, with SA, I crib from Microsofts own site, you "acquire the latest software automatically, spread payments annually and extend the workplace to the home." And Red Hat, as we know, has abandoned the home market except for people who like the bleeding edge of Fedora technology.
After talking to end-users, IT staffers and resellers, I think I know why Red Hat has been successful. The big reason to go with either plan is so that youre guaranteed to get the latest software at no charge over the course of the agreement. With Red Hat, though, you also get system management support, a lot of it, via RHN (Red Hat Network).
For businesses that are still getting their feet wet with Linux, RHN can make the difference between swimming to commercial success and drowning in technology confusion.
With Linux, you also can see real improvements with the operating system on a yearly basis. Even without the major jump up in enterprise functionality that will come with the next version of RHEL (Red Hat Enterprise Linux), which will be based on the Linux 2.6 kernel, you can see—and use—the improvements from one update of Linux to the next.