So, what's the difference between these two groups?

1. Sliding block / tile puzzle games
2. Genre: Jigsaw puzzle

Sliding Block Puzzle

Jigsaw Puzzle

Jigsaw puzzles are about finding the right location of a finite number of piece that can be moved freely.

Sliding puzzles are about finding a way to move all pieces to their correct position, but the pieces are locked in a raster and cannot overlap each other. You need to slide them in the right order.

I can't believe I spent my whole life thinking that "jigsaw puzzle" was the name of the sliding block/tile puzzle. In Portuguese, jigsaw puzzles are only called "puzzles" ("quebra-cabeça" is the word), so I guess I thought that the sliding tile variant was called "jigsaw". Man, I'm feeling really dumb now. =(

Edit: worst of all, I never really thought about what jigsaw means (the power tool). I just can't believe that I never made the connection.

It's just the white man's plan to confuse South Americans into obedience.
Yeah, I need work on this conspiracy theory stuff. :p

A jigsaw puzzle is just a fragmented image that requires reassembly, while a sliding tile puzzle constrains the way puzzle pieces can be moved and dictates that they be moved in a certain order. Sliding tile puzzles are descendants of the historical 15 puzzle (http://en.wikipedia.org/wiki/Fifteen_puzzle)