I've written a couple of surveys on this very subject for SearchSecurity and some similar stories for InformIT.com. SearchSecurity has information broken into vendor-specific security certs and vendor-neutral security certs.
To check out the InformIT.com stuff, search on "Tittel security overview" -- they use dynamic URLs for database retrieval, so I can't give you a specific URL.
This should tell you most or everything of what you need to know. Read this stuff, then follow up with any additional questions you might have.
This was first published in June 2002