Rapid Storage Technology 9.5 is the new version of Matrix Storage Manager 8.9. Basically in moving its RAID drivers/software from 8.x to 9.x, Intel have changed the name.
However, there are two things to note
a) Rapid Storage Technology has not been officially released by Intel, so is not yet supported. If you want official, supported drivers you are better off downloading direct from Intel. The version at station-drivers is a leaked driver, and may differ slightly from the official version when Intel releases it.
b) neither version passes TRIM - so apart from a prettier UI, it is doubtful you'll seen any substantial difference between Rapid Storage Technology and Matrix Storage Manager.
Matthew