Avançado vs. atacante
The words avançado and atacante both refer to offensive football players whose main job is to score goals. The primary difference is regional: avançado is utilized in European Portuguese (Portugal), while atacante is the standard term in Brazilian Portuguese.
Avançado
B1In Portugal, avançado is the specific term for a forward. It refers to a player positioned high up the pitch near the opponent's goal. Note that in European Portuguese, related vocabulary like equipa (team) and golo (goal) are commonly used alongside this word.
O treinador decidiu colocar mais um avançado no jogo.
(The coach decided to put one more forward in the game.)
Cristiano Ronaldo é considerado um dos melhores avançados do mundo.
(Cristiano Ronaldo is considered one of the best forwards in the world.)
A equipa precisa de um avançado que saiba cabecear bem.
(The team needs a forward who knows how to head the ball well.)
O defesa passou a bola diretamente para o avançado.
(The defender passed the ball directly to the forward.)
Atacante
B1In Brazil, atacante is the general term for an attacking player or striker. It comes from the verb atacar (to attack). In this variety of Portuguese, you will often hear time (team) and gol (goal) used in the same context.
O atacante brasileiro marcou três gols na partida de ontem.
(The Brazilian striker scored three goals in yesterday's match.)
Neymar joga como atacante e cria muitas oportunidades.
(Neymar plays as a forward and creates many opportunities.)
O time está procurando um novo atacante para a temporada.
(The team is looking for a new attacker for the season.)
Aquele atacante é muito rápido e habilidoso.
(That forward is very fast and skillful.)
Summary
Use avançado when speaking or writing in European Portuguese to refer to a forward. Use atacante when communicating in Brazilian Portuguese to refer to the same position. While both mean a player who attacks, the regional preference is very strong.