Profundidade vs. profundeza
Both profundidade and profundeza translate to deepness or depth in English, but they belong to slightly different contexts. The word profundidade is the standard, everyday term used for measurable depth, whether literal or intellectual. On the other hand, profundeza carries a more literary, dramatic, or poetic tone. It often describes a mysterious, vast, or emotional abyss, and is very frequently used in its plural form as profundezas to mean the depths.
Profundidade
B1This word is used to describe the physical, measurable distance from the surface to the bottom of an object or body of water, as well as the level of intellectual complexity or detail in a subject.
A piscina do clube tem três metros de profundidade na área mais funda.
(The club's pool has three meters of depth in the deepest area.)
O professor explicou o contexto histórico com muita profundidade.
(The teacher explained the historical context with a lot of depth.)
Os engenheiros precisam calcular a profundidade exata do buraco antes de construir.
(The engineers need to calculate the exact depth of the hole before building.)
Esta câmera permite ajustar a profundidade de campo muito facilmente.
(This camera allows you to adjust the depth of field very easily.)
Faltou profundidade aos argumentos apresentados pela equipe de vendas.
(The arguments presented by the sales team lacked depth.)
Profundeza
C1This word represents a vast, unmeasurable, poetic, or abstract sense of deepness, frequently used to describe the most remote, unknown, or intensely emotional parts of a place or mind.
Muitas criaturas desconhecidas vivem nas profundezas do oceano.
(Many unknown creatures live in the depths of the ocean.)
O poeta escreveu sobre a mágoa que sentia na profundeza de sua alma.
(The poet wrote about the sorrow he felt in the deepness of his soul.)
As lendas antigas falam de monstros que habitam as profundezas da terra.
(Ancient legends speak of monsters that inhabit the depths of the earth.)
Ele olhou para a profundeza escura da caverna e sentiu um calafrio.
(He looked into the dark deepness of the cave and felt a shiver.)
O amor que eles compartilham alcança as maiores profundezas do coração.
(The love they share reaches the greatest depths of the heart.)
Summary
To summarize, you should use profundidade when you are talking about literal measurements, spatial dimensions, or the thoroughness of an intellectual analysis. You should choose profundeza when you want to evoke a literary or emotional feeling, especially when referring to the bottommost, uncharted realms of nature or human emotion.