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

No

While the verb "lanchar" retains the same core meaning (to have a snack) in both dialects, there is a difference in typical usage and the associated vocabulary. In Brazil, "lanchar" is frequently used when referring to the act of eating a "lanche," which is often a heavy item like a burger or a substantial sandwich. In Portugal, "lanchar" is more strictly tied to the ritual of the mid-afternoon meal. Furthermore, when referring to the food itself, Brazilians often use "lanche" as a synonym for "sanduíche" (sandwich), whereas a Portuguese person would typically use the word "sandes." There are also differences in the names of ingredients, such as presunto in Brazil versus fiambre in Portugal.

Brazilian Portuguese Examples

1. Eu adoro lanchar um hambúrguer com batata frita. (I love snacking on a burger with fries.)
2. Vamos lanchar algo rápido antes do cinema? (Let's grab a quick snack before the movie?)
3. O meu lanche favorito é um lanche de presunto e queijo. (My favorite snack is a ham and cheese sandwich.)
4. Ela costuma lanchar uma fruta bem cedo. (She usually snacks on a fruit very early.)
5. Eles foram lanchar na lanchonete da esquina. (They went to have a snack at the corner snack bar.)

European Portuguese Examples

1. Eu adoro lanchar uma sandes de queijo. (I love snacking on a cheese sandwich.)
2. Vamos lanchar algo rápido antes do cinema? (Let's grab a quick snack before the movie?)
3. O meu lanche da tarde é sempre uma sandes de fiambre. (My afternoon snack is always a ham sandwich.)
4. Ela costuma lanchar uma fruta bem cedo. (She usually snacks on a fruit very early.)
5. Eles foram lanchar à pastelaria. (They went to have a snack at the pastry shop.)