Compartilhar vs. partilhar
The words compartilhar and partilhar both mean "to share," but their usage depends heavily on the region (Brazil vs. Portugal) and sometimes on the intent of dividing versus partaking. In general, compartilhar is the standard in Brazil, while partilhar is the standard in Portugal.
Compartilhar
A2This is the most common term in Brazilian Portuguese for sharing experiences, space, news, or social media content. It implies using or experiencing something jointly with others rather than physically cutting it into pieces.
Eu vou compartilhar minha localização com você pelo celular.
(I will share my location with you via mobile.)
Nós precisamos compartilhar o conhecimento com os alunos.
(We need to share knowledge with the students.)
Ela decidiu compartilhar o escritório para economizar dinheiro.
(She decided to share the office to save money.)
Por favor, não esqueça de compartilhar este vídeo.
(Please, do not forget to share this video.)
Partilhar
B1This is the dominant term in European Portuguese for all types of sharing. In Brazilian Portuguese, it is less common and often refers specifically to dividing a physical quantity into parts, like food or an inheritance.
Vamos partilhar esta pizza entre nós quatro.
(Let's share (divide) this pizza among the four of us.)
Os irmãos tiveram problemas ao partilhar a herança.
(The siblings had trouble sharing (dividing) the inheritance.)
Gosto de partilhar momentos felizes com a família.
(I like to share happy moments with the family (Standard European Portuguese usage).)
O monge decidiu partilhar o pão com o pobre.
(The monk decided to share the bread with the poor man.)
Summary
Use compartilhar if you are speaking Brazilian Portuguese, especially for digital content or abstract ideas. Use partilhar if you are speaking European Portuguese, or if you strictly mean dividing a physical item into portions.