Spring Boot applications are slightly different from tradition Java web applications (or Jakarta EE applications) in that they by default create a
JAR file with an embedded server in it, rather than a traditional
WAR file that’s deployed to a standalone Servlet container or fully featured Java EE server.
Alternatively, Spring Boot applications can be packaged as
WAR files, too.
See the Spring Boot documentation for instructions on how to do this.
The main differences between
WAR packaging are as follows:
no need for a server binary install; a Java Runtime is all that’s needed
bigger package size
a separate Java Servlet container is needed
free choice of servers, including Jetty, Tomcat, WildFly, GlassFish, and others
smaller package size
You can read more about Spring applications and how to deploy them on the official Spring website.