Is it that there is one InDesign Object Model, and the difference is just that with uxp we can use more modern javascript syntax? Or is it that there are two Object Models depending on whether we are writing extendscript or uxp?
However we should be aware that the APIs are different. Many functions of the UXP “indesign” module are identical which those of ExtendScript and I still use the old documentation for programming in that area (because it is so much better structured on Gregor’s indesignjs.de). But sometimes that fails, because the API is different.