Streaming Spotify complete album, but some cuts are not the original album version

So, I stream a bit, mostly for new music discovery. I use Spotify Premium as I find it to be very intuitive to use and they have a huge library.

Sometimes, when I stream a complete album, I find that some of the cuts are not the original album version. I wonder why?

An example from my listening session last night:

The Breeders - "Last Splash"

The version of "Saints" -  listed as track # 13 on the album on Spotify and also on my original CD. The version on Spotify is not the same as the version on my original CD. Curious why this would be the case?

Any thoughts, comments, etc.? Not a big deal, but I prefer the original CD version and wanted to send it to my teenage son. However, the only version on Spotify is the one included on their album, which is not the original IMHO.

Learned long time ago, after wasting a,lot of money on “best of” lp’s’ CDs. 
 Most best of CDs cut the beginning, or middle, the end, cut seconds of many songs.

from then on, only buy the full album or cd.
@arcticdeth  - Thanks for your response. However it has nothing at all to do with this album - "Last Splash" which was the most popular studio release from The Breeders, and is not a "best of" CD.
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