Some constructions are different. For example, in Br Portuguese it's quite common to use continuous forms using the ending "-ndo" in the same way as english speakers use "-ing" - in opposite to the form used in portugal "a + infinitive". Examples: estou falando (Br) estou a falar (Pt) I'm speaking "Mesóclises" are avoided in Brazilian Portuguese, and reflexive/obliquous pronouns usually can start a phrase: Me faz um favor? É claro que o faço! (Br) Faz-me um favor? É claro que faço-o! (Pt) Brazilian Portuguese has many different accents depending on the region it's spoken - but it's usually spoken more slowly than in Portugal. Some words differ or are exclusive in each variant.

we have many different words. Brazil wasn't only colonized by the portugueses. Many words that we use here came from the French (eg "abajour", "lingerie"), other ones from the Italian, African, Guarani (indigenous language), German, Polish and many other languages of people who came to live in Brazil.

Well... The difference between them is such as British English and USA English . If someone want to learn english as a second language they look for a greatest place. Portuguese the same.... Portugal is smaller than Brazil. The city of Rio de Janeiro has the same size than Portugal country. PT - BR and PT - PT is different like British english and USA english. Some words and some pronunciation. take care before choose one and Good Luck!

A good curse will embrace both. The written language is the same. If you are just starting to learn Portuguese, than Iberian, African or Brazilian specificities are not that important for now. Usually, Brazilian must common pronunciation is slower and European is more like Spanish.

I know far more Brazilian people than Portuguese, so I haven't heard the differences (...yet! Am interested to know also!). But to answer your second question: who will you talk to? Where are your friends/contacts? If your friends are all in Lisboa, then there's not much reason to practice the brasiliero style, and vice versa. So pick the style based on who you will talk to. :)