The answer maybe comes a little late, but for other with the same question, a short explaination.
In steem there are several configuration for running a node. There is the p2p node, which is the right one, if you want to run a node (witness) only for mining steems. For that, parts of the blockchain are not needed and the installation works with minimum requirements. A full node has a complete (or partial configuration) copy of the blockchain (with posts, follower, etc.). Also it has a web socket, which handles http or https (ssl certificate is needed) traffic. The installation of both version are nearly the same, you define the plugins with the compilation or docker build (or image).
Hope I could help someone out with this answer! For me, it took a longer time to find out, because synchronization of the blockchain takes some days by now. In case of syncing the whole blockchain, it takes about 70GB diskspace, otherwise you can download it, what takes about 160GB to install.!