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

Yes

The word "melancias" is identical in both Brazilian and Continental Portuguese in terms of meaning, spelling, and grammar. The only difference lies in pronunciation. In Brazilian Portuguese, the "s" at the end of the word is typically pronounced as a dental [s] (like the "s" in "sun"), whereas in many regions of Portugal, it is pronounced as a postalveolar [ʃ] (sounding like "sh"). Additionally, the vowel sounds may vary slightly in terms of openness depending on the specific regional accent.

Brazilian Portuguese Examples:

1. Eu comprei duas melancias grandes no mercado. (I bought two large watermelons at the market.)
2. Você quer comer um pedaço de melancia? (Do you want to eat a piece of watermelon?)
3. As melancias estão bem docinhas hoje. (The watermelons are very sweet today.)
4. Não gosto de melancia com muito caroço. (I don't like watermelon with too many seeds.)
5. Vamos fazer um suco de melancia geladinho. (Let's make a very cold watermelon juice.)

Continental Portuguese Examples:

1. Comprei duas melancias grandes no supermercado. (I bought two large watermelons at the supermarket.)
2. Queres comer um pedaço de melancia? (Do you want to eat a piece of watermelon?)
3. As melancias estão muito doces hoje. (The watermelons are very sweet today.)
4. Não gosto de melancia com demasiados caroços. (I don't like watermelon with too many seeds.)
5. Vamos fazer um sumo de melancia bem fresco. (Let's make a very fresh watermelon juice.)