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

Yes

The spelling, meaning, and grammatical function of "cadeiras" are identical in both Brazilian and Continental Portuguese. The only difference is pronunciation. In Brazilian Portuguese, vowels are typically more "open" and clearly articulated, making the syllables easy to distinguish. In Continental Portuguese, there is a high degree of vowel reduction, meaning unstressed vowels (like the "e" and "i" in cadeiras) are often shortened, closed, or almost swallowed in natural speech.

Brazilian Portuguese Examples

1. As cadeiras da sala são muito confortáveis. (The living room chairs are very comfortable.)
2. Eu preciso comprar quatro cadeiras novas para a cozinha. (I need to buy four new chairs for the kitchen.)
3. Você pode puxar uma das cadeiras para sentar? (Can you pull one of the chairs to sit down?)
4. As cadeiras de plástico estão lá no quintal. (The plastic chairs are out there in the backyard.)
5. Nós limpamos todas as cadeiras de madeira hoje. (We cleaned all the wooden chairs today.)

Continental Portuguese Examples

1. As cadeiras da sala são muito confortáveis. (The living room chairs are very comfortable.)
2. É necessário comprar quatro cadeiras novas para a cozinha. (It is necessary to buy four new chairs for the kitchen.)
3. Podes puxar uma das cadeiras para te sentares? (Can you pull one of the chairs to sit down?)
4. As cadeiras de plástico encontram-se no quintal. (The plastic chairs are in the backyard.)
5. Limpámos todas as cadeiras de madeira hoje. (We cleaned all the wooden chairs today.)