The interfaces BeanFactory and ApplicationContext represent the Spring IoC container. Here, BeanFactory is the root interface for accessing the Spring container. It provides basic functionalities for managing beans.

On the other hand, the ApplicationContext is a sub-interface of the BeanFactory. Therefore, it offers all the functionalities of BeanFactory.

Furthermore, it provides more enterprise-specific functionalities. The important features of ApplicationContext are resolving messages, supporting internationalization, publishing events, and application-layer specific contexts. This is why we use it as the default Spring container. 

https://www.baeldung.com/spring-application-context