@dobey Thanks. Okay, that simple. I thought they were for different builds like for example in this case: https://www.phonemore.com/models/samsung/galaxy-note-4/ and each would need a different OEM ...

@dobey Thanks for the contributions.
On my LG Nexus 5 it says (with UBports-installer ubuntu_touch already installed) the build is "aosp_hammerhead-userdebug 5.1.1 LMY48W 1086 test -keys". But if I look here https://developers.google.com/android/images#hammerhead LMY48W is for 5.1.1 of "shamu" for Nexus 6 ... Now I don't know which of the 13 versions of 6.0.1 for Nexus 5 to choose for my phone. And I don't see where to look up the model number of the phone running already under ubuntu touch ...