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

No

While the fundamental meaning of "demorou" (the third-person singular past tense of demorar, meaning "to take a long time" or "to delay") is the same in both variants, there is a significant difference in typical usage.

In Brazil, "demorou" is frequently used as a slang interjection. It can mean "It's a deal!", "Let's do it!", or "Count me in!" when agreeing to a plan. It can also be used sarcastically to mean "It took you long enough!" In Portugal, the word is almost exclusively used in its literal sense to describe the duration of an event or a delay, and you would not use "demorou" as a standalone way to agree to a social invitation.

Brazilian Portuguese examples:

1. O ônibus demorou muito para chegar hoje. (The bus took a long time to arrive today.)
2. — Vamos na festa mais tarde? — Demorou! (— Shall we go to the party later? — It's a deal!)
3. Ele demorou uma eternidade para se arrumar. (He took an eternity to get ready.)
4. Demorou, hein? Achei que você não vinha. (Took you long enough, huh? I thought you weren't coming.)
5. A encomenda demorou a chegar, mas finalmente veio. (The package took a long time to arrive, but it finally came.)

Portuguese (Portugal) examples:

1. O autocarro demorou muito para chegar hoje. (The bus took a long time to arrive today.)
2. — Vamos ao cinema? — Combinado! (— Shall we go to the movies? — Agreed!)
3. Ele demorou uma eternidade a arranjar-se. (He took an eternity to get ready.)
4. Demorou a responder à minha mensagem. (He/she took a long time to reply to my message.)
5. A encomenda demorou a chegar, mas finalmente veio. (The package took a long time to arrive, but it finally came.)