To put it in boxing terms; in the first round we had the Sweet vs. Tony Blackburn (see here); a knock-out to the Sweet and strictly lightweight.
To kick off round two we have the Sweet vs. New World and 'Tom Tom Turnaround'. I think a technical knock-out to the Sweet in this lower middleweight contest.
Round three puts the Sweet up against journeymen Light Fantastic and 'Jeanie' (see here). A fair result would be a draw.
But the heavyweight championship of glam songs pits the Sweet against king of the ring David Bowie. It’s the ‘slammer in the glammer’, a ‘Hitter in the glitter’ a ‘Shake up with the make up’, its 'Blockbuster' vs. 'the Jean Genie'.
It’s a points win for the Sweet by virtue of it reaching # 1 in the UK charts.
The opening riff of the song is not the only thing they have in common. Both songs were released in 1972 and both were on the RCA record label.
The Sweet's single, written by Mike Chapman and Nicky Chinn, was recorded and released slightly later than Bowie's song, but it went on to reach #1 in the UK charts while "The Jean Genie" could only reach #2.
When asked about the songs similarities, Nicky Chinn stated: "Oh, absolute coincidence. The ridiculous thing was, of course, they were both on the same record label (RCA). But I know we had never heard Bowie's 'Jean Genie' and to the best of my knowledge he hadn't heard 'Blockbuster'.
There was a lot of fuss about it at the time. I think it's interesting to note, and again it was not a conscious thing on our part, but the riff is extremely similar to 'I'm A Man' by The Yardbirds. Fortunately, we went to No. 1 and Bowie went to 2." - Record Collector (1998) talking to Nicky Chinn and Mike Chapman