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

No

The difference lies in typical usage. In Brazilian Portuguese, "lanche" refers primarily to the food item itself—such as a sandwich, a burger, or any snack food. In Continental Portuguese, "lanche" refers more to the mealtime or the period of the day (the afternoon snack), while the food consumed during that period is more commonly referred to as a "sandes" or "sanduíche."

Brazilian Portuguese Usage

1. Vou preparar um lanche para você. (I'm going to prepare a snack for you.)
2. Este lanche de presunto está uma delícia. (This ham sandwich is delicious.)
3. A gente sempre pede um lanche à noite. (We always order some fast food at night.)
4. O lanche da escola é muito saudável. (The school snack is very healthy.)
5. Eu adoro um lanche bem recheado. (I love a very stuffed sandwich.)

Continental Portuguese Usage

1. As crianças estão a fazer o lanche. (The children are having their afternoon snack.)
2. Vou comer uma sandes ao lanche. (I am going to eat a sandwich during the afternoon snack.)
3. O lanche é servido às cinco horas. (The afternoon snack is served at five o'clock.)
4. Preparei uma sandes para o lanche. (I prepared a sandwich for the afternoon snack.)
5. Gosto de tomar um chá durante o lanche. (I like to have a tea during the afternoon snack.)