Just runs specified playbooks with specified parameters.
Build
This type of template should be used to create artifacts. The start version of the artifact can be specified in template parameters. Each run increments the artifact version.
Semaphore doesn't support artifacts out-of-box, it only provides task versioning. You should implement artifact creation yourself. Read the article Build and deploy to know how to do this.
Deploy
This type of template should be used to deploy artifacts to destination servers. Each deploy template associated with the build template.
This allows you to deploy a specific version of the artifact to the servers.