There are a few differences in written language, even though the base is the same. A few words are different, and there are some key diferences like brazilian portuguese not using the 2nd person of the singular (at least in conversational language), opting for a modified 3rd person.
Speaking-wise, the brazilian version has an extremely thick accent, that makes it either more or less pleasant depending on your taste, while portuguese have a generally more neutral speech. A fun (and quite accurate) comparison someone from neither country made to me once is that, if portugal was american english, brazil would be scottish.
'Læser du det portugisiske kort?' would be a direct translation. In English both 'the' and 'that' translate into 'det'. If you translate my sentence back into English you should therefore consider if you're speaking about 'the Portuguese map' (as opposed to a German one i.e.) or 'THAT (specific) Portuguese map' (that is old and outdated, i.e.)...