Sorry for the confusion. The term Bitcoin can be used to refer to the code that runs the Bitcoin network upon which the Bitcoin currency/token moves around and is stored. The inventors could probably have come up with different names for each of those things, but what can you do?

Cryptocurrency folks do sometimes take the open source Bitcoin code and make small (or large) changes to it in order to do their work. When they do this they create a separate codebase, separate network, and a separate currency. Almost inevitably they do so in such a way as to greatly benefit themselves and to fool you.