ATI All-In-Wonder Radeon cards (PCI and AGP) had two styles of install.

From 2000 to mid 2003, there were at least three separate installers that had to be installed in a specific order. 
The installers were: 
graphics drivers,
video capture drivers,
and control panels.
Because people don't seem to be able to read, there were many problems from out-of-order installs. ATI software has never been simple, it sort of "octopuses" itself into your computer, with bits and pieces all over the place, in order to run correctly. Video capture is, after all, a fairly complex task, and this was a rather advanced piece of hardware. 

When installed in the wrong order, it was difficult to uninstall and start over. At one time, ATI even had a "ATI removal" tool, to help in this process. Latter generation cards had added optional installers, to be installed after the core three installers, which included some Windows Media encoding options, as well as the TV guides and remote control features. You often found yourself installing 6-7 things on the new 2003 model cards.

For example, you'll notice how I've labeled the files 1st-5th on the v6168 package (the last ATI installer from the "separate installer" era):
ATI-6168package-1st-wdm.rar
ATI-6168package-2nd-wme.rar
ATI-6168package-3rd-cp.rar
ATI-6168package-4th-mdacdao.part1.rar
ATI-6168package-4th-mdacdao.part2.rar
ATI-6168package-4th-mdacdao.part3.rar
ATI-6168package-5th-hydra.part1.rar
ATI-6168package-5th-hydra.part2.rar
From late 2003 until the end-of-life of the card series (2005/2006), the three installers were merged into a single installer application named "Catalyst". Early versions showed you each of the drivers/utilities being separately installed, but as time went on that became transparent, as if it were a single install of a single program.

After the various drivers and control panels were installed, you installed ATI Multimedia Center (ATI MMC), that was used for capturing video, or to timer record TV shows. Then and now, this was the best tool for this card, having been designed specifically for the hardware.
NOTE: ATI MMC 8.x series also required the installation of DAO/MDAC package, adding yet another installer.
On top of all this, nothing from ATI would install until you had Windows DirectX 9 series (9.0c, I believe) installed correctly. Windows ME and early versions of XP came with DirectX 8 by default, which was not powerful enough to run the ATI video. This was another issue from the original 2000-2003 installer method, as some steps could not continue until DirectX9 was installed. Although a warning was usually given, again people did not read, clicked OK (thereby ignoring the warning), and the install process would abort. Again, you'd have an incomplete mess installed, and it wasn't always easy to uninstall and start over.

A lot of people whinged/whined and complained in forums about this (or in reviews online), but this was still a very mild install procedure compared to other complex/professional video cards of the era, such as Matrox or Avid hardware. The realtime Matrox cards, with their heavy Adobe suite integration, made ATI installation look simple. I still firmly believe the complaints were all related to lazy users and/or people that did not read the instructions. It was rare to find a legitimate install issue, when instructions were read and followed. It was not a dummy-friendly hardware/software combo, it took some effort to set up -- you couldn't just cram a disc in a CD drive, hit "go" and walk away, returning 10 minutes later ready to record some TV.

I hope this historical insight helps clarify the variances in files