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

Yes

The word "loja" is identical in meaning, spelling, and grammatical gender between Brazilian and Continental Portuguese. The only difference lies in pronunciation. In Brazil, vowels tend to be more open and clearly articulated. In Portugal, unstressed vowels are often reduced or "swallowed" (vowel reduction), making the "o" in "loja" sound much more closed and subtle.

Brazilian Portuguese Examples

1. Vou na loja comprar um presente. (I'm going to the store to buy a gift.)
2. Essa loja tá sempre cheia. (This store is always full.)
3. A loja de roupas abriu cedo hoje. (The clothing store opened early today.)
4. Você conhece uma loja boa de eletrônicos? (Do you know a good electronics store?)
5. Preciso passar na loja para trocar essa camiseta. (I need to stop by the store to exchange this t-shirt.)

Continental Portuguese Examples

1. Vou à loja comprar um presente. (I'm going to the store to buy a gift.)
2. Esta loja está sempre cheia. (This store is always full.)
3. A loja de roupa abriu cedo hoje. (The clothing store opened early today.)
4. Conheces uma boa loja de eletrónicos? (Do you know a good electronics store?)
5. Tenho de ir à loja para trocar esta t-shirt. (I have to go to the store to exchange this t-shirt.)