Futures companies are intermediaries between futures traders and futures exchanges. Because most traders (except self-operated members of the exchange) cannot trade directly on the exchange, they must go through intermediaries. Futures companies are such intermediaries.
Trading platform refers to the trading means (or trading channels) between brokers and futures companies and exchanges. In the past, it was a manual telephone transaction, but now it is a computer-aided ordering system. So it used to be an artificial platform, but now it is a computer platform. The trading platform uses different systems, such as Windows and Linux, and uses different databases.