Is the word então the same in Brazilian and European Portuguese?

No

While the fundamental dictionary meaning of "então" (then, so, in that case, at that time) is identical in both dialects, there are differences in typical usage and pronunciation.

In Brazilian Portuguese, "então" is used much more frequently as a conversational "filler" or discourse marker to start sentences, bridge topics, or signal a transition (similar to the English "so..."). While this occurs in Portugal, a Portuguese speaker is much more likely to use words like portanto (to indicate a logical consequence), pois (as a filler), or bem (to transition) to achieve the same effect. Additionally, the pronunciation differs: Brazilian Portuguese tends to have more open, resonant vowels, whereas Continental Portuguese features more closed, reduced, or "clipped" unstressed vowels, making the word sound sharper and more compressed.

Brazilian Portuguese Usage

1. Então, o que você vai fazer hoje? (So, what are you going to do today?)
2. Eu estava com fome, então comi um lanche. (I was hungry, so I ate a snack.)
3. Então, você viu o que aconteceu? (So, did you see what happened?)
4. Ele não estudou, então tirou uma nota baixa. (He didn't study, so he got a low grade.)
5. Então, vamos começar a reunião? (So, shall we start the meeting?)

Continental Portuguese Usage

1. Portanto, o que é que vais fazer hoje? (So, what are you going to do today?)
2. Estava com fome, por isso comi um lanche. (I was hungry, so I ate a snack.)
3. Bem, viste o que aconteceu? (Well, did you see what happened?)
4. Ele não estudou, logo, tirou uma nota baixa. (He didn't study, so/consequently, he got a low grade.)
5. Pois, vamos começar a reunião? (Well/So, shall we start the meeting?)