Contractium is a Dapp (Decentralized application), which has its own backend code running on Ethereum network.
Contactium has the fronted code and user interfaces written in AngularJS that makes the calls to its backend, which is mainly written in Node.js.
So, Contractium = Fronted + Decentralized server, and Contractium's contract are the code that runs on the global Etereum decetralized peer-to-peer network.