I am trying to copy structures between worlds on my PS4 Edition of Minecraft. However, when I save structures either in memory or to disk, I am unable to load them into another world on the same system. Is this possible or am I doing something wrong?
There isn't a PS4 Java edition, if you are playing on PS4 you're playing Bedrock edition. Currently the structure blocks on bedrock do not have the full functionality of Java and there is no way to transfer those structure file to another world without the help of third party tools. You would have to convert your world save and transfer it to a computer where you use a program called McEdit, download the Unified verision this will save you a step (converting your world to Java). With McEdit you will be able to copy structures.