A model that you need to use a device can be much simpler than a model that you need to fix the device if it is broken which in turn may be simpler than a model

A model that you need to use a device can be much simpler than a model that you need to fix the device if it is broken which in turn may be simpler than a model required to build the device from scratch, etc. I saw "how does it work" used as "how to use it" on American TV https://www.youtube.com/watch?v=MEFXhopARyw https://www.youtube.com/watch?v=MEFXhopARyw