Bit of a newbie question Are all Ubuntu apps the same regardless of the device for instance if I made an app for Ubuntu on a jetson tx2 developer kit would the code be same as a Ubuntu app ran on a MacBook?
Depends on what you mean with "the code". The binaries have to be compiled for the target architecture, so the machine code will differ for these two machines as AlexP pointed out. But the packages are usually based on the same source code, so applications of the same version should provide the same functionality and behaviour as far as supported by the hardware and the environment (depending on the available libs).
For a more detailed answer we need to know what the intention of this question is.