spring-boot-starter-tomcat vs spring-boot-starter-web

Since #1 supports Tomcat why would one want to use #2?

spring-boot-starter-web contains spring-boot-starter-tomcat. spring-boot-starter-tomcat could potentially be used on its own if spring mvc isn’t needed (contained in spring-boot-starter-web).

Here is the dependency hierarchy of spring-boot-starter-web:

What are the differences?

spring-boot-starter-web contains spring web dependencies (including spring-boot-starter-tomcat):

spring-boot-starter
jackson
spring-core
spring-mvc
spring-boot-starter-tomcat

spring-boot-starter-tomcat contains everything related to an embdedded tomcat server:

core
el
logging
websocket

What if you want to use spring mvc without the embedded tomcat server?

Just exclude it from the dependency:

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <exclusions>
            <exclusion>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-tomcat</artifactId>
            </exclusion>
        </exclusions>
    </dependency>