I've searched and read maven [docs](https://maven.apache.org/pom.html), but didn't find the answer. I'm new to java, so please forgive me if this is a duplication.

In our company project I see a pom defines such elements:

```
    <properties>
      <application.main.class>com.xxx.classfoo</application.main.class>
      <exec.main.class>com.yyy.classbar</exec.main.class>
      ...others...
    </properties>

```

So the question is what's the differences between them? Their names seem so much alike!