A bookmark is a place holder. it allows a user to return to a place and a state the dashboard was in to return a particular result. as such each time you apply the bookmark the same filter and location in the app is returned to the data contained there can have moved on based on how many reloads of data has occurred since the bookmark was applied.
Stories are snapshots in time. what toy recird in your stories is the state of the data at a given point in time. this will stay the same each time you return to the story so it allows you to look back at the state of the app regardless of how the data model has changed since.
Stories are historical observations and bookmarks are placeholders on the current app to repeat your observations.