Here are two good examples of that. These are the original versions of the respective songs; note how different they are from the ones that were eventually released.
The original post for ‘The Wild One’ can be found here.
The production on the single version is a lot brighter, and the original version has a more prominent male backing vocal.
This version of ‘Fox on the Run’ can be found on the “Desolation Boulevard” album from 1974 produced by Chinnichap. In 1975, Sweet went back into the studio to re-arrange and record a more pop-oriented version of the track.
It was Sweet's first self-written and self produced single. The single reached #2 in the
Suzi Quatro: The Wild One (album version)
Sweet: Fox on the Run (album version)