I really like the concept here. I'm actually working on a game with the same world swapping mechanic, so I was excited to see what you did with it. The transitions work nicely and the puzzle design is straight forward and intuitive. Well done! Unfortunately, the physics on the objects is a little too slippery. I got really frustrated trying to line up the beams perfectly in a later level because it kept slipping the moment I tried jumping onto it. The spring also wouldn't stay in place when I tried to jump on it, causing it to go off the edge and off screen. I understand the slight rotation while picking something up, but it makes slight adjustments to existing objects unnecessarily difficult.
Overall, great entry! I was really happy with how your game turned out. Well done :)