So when is a kumiki puzzle different - that is a question I have been pondering recently. I was first made aware of potential differences in identical looking puzzles by Martin Watson. He showed that the barrel can have the first move (which is usually 2 pieces) either horizontally, vertically, or from the top. This is basically a rotation of the first move.
So I started looking to see if any of the puzzles that looked the same were in fact different in construction.
Apart from the the first move being along a different axis there are a number of differences that can be found in Kumiki puzzles.
Firstly there is a completely different key piece or pieces
So these two pagoda puzzles look very similar, there are some cosmetic differences to the top of the tower, and slight differences in the shaping of the roof pieces. However, they have very different first moves.
The one on the left a solid key piece that simply slides out.
Whilst the one on the right has a twist key which releases the rest of the puzzle
So obviously both puzzles need to be in the collection.
This kind of difference can be seen on very common puzzles too, for instance the cube puzzle is one of the basic puzzles, and the standard has 2 pieces that slide out together. However, there is a version that only has a single key piece.
The same with the planet / Jupiter / Flying saucer puzzle.
The interesting thing is when there are very different moves, and a great example of this is the Trolley. Sometimes labeled as San Francisco, or even "Desire". There are 3 different first moves that I am aware of, a solid key piece that slides out of the middle of the trolley - a bit like the common pig puzzle, 2 pieces that slide out on the underside of the puzzle, and a single piece that slides out of the top.
See on the image below for the each example.
So you can see that next time you see a puzzle and think " I have one of those ", you may want to look a little more carefully.