Just because whoever wrote the tab thinks it is 100% correct it does not make it so. Similarly just because someone else thinks he knows 100% how a song does it does not make it so. I've read tabs that claim to be 100% correct that were wrong, and I've been "corrected" by other musicians before that were also wrong.
I've also been fairly convinced that what I was playing was correct, only to later hear something new.
Being able to hear and differentiate all the notes is something I found really hard when I started, but got much better at over time. You just have to keep practising.
For now I would read all the tabs you can find, listen to all the youtube covers/versions/isolated bass tracks, ask other people like your friend to show you how they thinks it goes, and then make your own judgement.