Banco vs. banca
The Spanish words banco and banca can be confusing because both can relate to banking and benches. However, they have distinct primary meanings and uses that are important to distinguish.
Banco
A1Banco is a masculine noun that most commonly refers to a specific financial institution (a bank) or a bench you sit on, typically in a public place like a park. It also has several other meanings, such as a workbench, a collection of resources (like a data or blood bank), or a school of fish.
Tengo que ir al banco a depositar este cheque.
(I have to go to the bank to deposit this check.)
Nos sentamos en un banco para descansar un rato.
(We sat on a bench to rest for a while.)
El carpintero organizó sus herramientas sobre el banco de trabajo.
(The carpenter organized his tools on the workbench.)
El hospital necesita urgentemente donaciones para su banco de sangre.
(The hospital urgently needs donations for its blood bank.)
Los pescadores se alegraron al encontrar un gran banco de sardinas.
(The fishermen were happy to find a large shoal of sardines.)
Banca
B1Banca is a feminine noun that primarily refers to the banking industry or system as a whole—the abstract concept of banking. It can also mean a bench, but often a smaller, simpler one without a back. Other key meanings include the substitutes' bench in sports, the house in gambling, or the seating for a group in a parliament.
La regulación de la banca es fundamental para la economía del país.
(The regulation of the banking system is fundamental for the country's economy.)
Mi hermano trabaja en la banca de inversión desde hace diez años.
(My brother has worked in investment banking for ten years.)
Después de una falta, el entrenador sentó al jugador en la banca.
(After a foul, the coach sat the player on the bench.)
En el juego de blackjack, la banca se planta con 17.
(In the game of blackjack, the house stands on 17.)
La abuela usaba una pequeña banca para alcanzar los estantes altos de la cocina.
(Grandma used a small stool to reach the high shelves in the kitchen.)
Summary
In essence, think of banco as the specific and physical, and banca as the general and abstract. You go to a banco (a bank building) to do business with the banca (the banking system). You sit on a banco in the park, while a substitute player sits on the banca during a game.