I would like to host a wordpress site. But I have a owncloud bitnami VM that is works very well.
Is it enough to set different domains or subdomains in apache configuration?
As you are using a Bitnami installation, you can download the Bitnami Wordpress Module: https://bitnami.com/stack/lamp/modules
After the installation, you will have both Owncloud and Wordpress. If you don't like the default configuration, you can adapt the Apache prefixes and virtual hosts to fix your needs.