As far as I know, there are 7 different official Final Fantasy VII puzzles; Cloud, Tifa, Aerith, Red XIII, Cloud&Chocobo, Midgar and Cloud&Chocobo Clock. The jigsaw puzzles were manufactured in 1997 by a Japanese company Amada Printing, as Amada Artbox series.

Cloud, Tifa, Aerith and Red XIII puzzles each have 108 pieces, making them the smallest of the puzzles.

The Cloud&Chocobo Puzzle has 500 pieces.

The Midgar Puzzle has 1000 pieces.

I have no information on how many pieces are in the Cloud & Chocobo Clock Puzzle.