StreamBIM Capture is a module for capturing issues, discussions or simply just creating personal notes related to the design or physical built elements. All of them with a model location, so you can always go back look and explore the issue with the current designed model, photos, drawings attached. This means that the foundation of the discussion or the decision to be made is unambiguous with an interdisciplinary model in front of you.
Capture basic is primarily a module for discussions with chat-like functionality (call it a BIM chat), or for personal notes/memos.
If you upgrade to Capture Pro, workflows can be defined by project administrators and control user rights on the topics. Who can create, assign, close, set due date etc. There's also a powerful filtering of topics and reporting of such available.
StreamBIM Capture can be found behind the thumbtack in StreamBIM