A Power BI Dataset is a series of Power Query queries that have been shaped in a DAX model. Each dataset can combine different files, database tables and online services all into one tabular model. In our cookie analogy, these are all different “ingredients”.
Unlike SSRS, a dataset in Power BI does not represent a single table or query of data. A dataset should be considered more like a “flavor” of data used to accomplish a specific type of reporting: financial, operational, HR, etc. So in our analogy, the dataset is the “raw dough”.
So in Power Query, you are going to have a set of queries which each combine a data source with a usually linear set of transformations.
The pie chart cookie is the first one I would have eaten, if only to eliminate it.