I think the difference is focus of the end point much as the difference between 'purpose' and 'goal' in English.
In English, 'purpose' as in 'The purpose' refers not to the goal but the job of something. For example: The purpose of the intervention is to help children. Here 'purpose' is similar to 'formål' and the sentence above.
Compare: Our goal (end point) is to help children. Here the sentence is not talking about a process but the result of the process. This, I think, would be how 'mål' would be used. Giving a sentence something like: Målet er å hjelpe barn.
I am not a native speaker, so I could be talking total rubbish. However, my dictionary appears to suggest the difference I have offered here.
For me personally, it took a long time for me to hear things being pronounced & I'm still not 100% on certain words. I'm currently living in Norway and have been attending language school through the immigration program since August. Being surrounded by the language has helped me pick up on different pronunciations but I'm still not good at doing it myself. So maybe just practicing listening exercises more can help you. (and me) Lykke til!