Nav message files clarification

I’d like to know what the difference is between .XXn RINEX files as published by navigation stations such as the Brussels one, bruxXXXX.XXn, and the broadcast .XXn files. I’m asking this because when I try to use the .XXo station files together with brdc .XXn files, the rtklib tool won’t give me anything (what it calls solutions, i.e. .pos files containing actual coordinates), while when I record the same .XXo files using my smartphone, I can freely use the brdc .XXn files to obtain my phone’s coordinates.

Is there any sort of clarification or a link to a resource explaining these things?