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

No.

While the spelling and basic meaning are identical, there are significant differences in grammar, typical usage, and vocabulary. In Brazil, "prepara" is frequently used as the imperative for the pronoun você, often paired with the reflexive "se" (e.g., se prepara). In Portugal, "prepara" is the second-person singular (tu) form, and the reflexive pronoun must be attached to the end of the verb (e.g., prepara-te). Additionally, while the word itself is the same, the objects it refers to often differ in vocabulary (e.g., trem vs. comboio), and the pronunciation differs, with Brazilians using more open vowels and Portuguese speakers using more closed or reduced vowels.

Brazilian Portuguese Examples:

1. Se prepara, o trem já vai partir! (Get ready, the train is about to depart!)
2. Prepara a geladeira para o verão. (Prepare the fridge for the summer.)
3. Prepara o lanche antes do ônibus chegar. (Prepare the snack before the bus arrives.)
4. Prepara o seu celular. (Prepare your cell phone.)
5. Se prepara para a viagem! (Get ready for the trip!)

Continental Portuguese Examples:

1. Prepara-te, o comboio já vai partir! (Get ready, the train is about to depart!)
2. Prepara o frigorífico para o verão. (Prepare the fridge for the summer.)
3. Prepara o lanche antes do autocarro chegar. (Prepare the snack before the bus arrives.)
4. Prepara o teu telemóvel. (Prepare your mobile phone.)
5. Prepara-te para a viagem! (Get ready for the trip!)