Worksheets are best for external 2d information. Usually, such as placing the site plan or a DPF/DWG/TIFF based detail. Then placing that worksheet onto a layout. However, worksheets can contain any 2d information, no matter what its origin. The worksheet is not linked to the model in any way.
Details are usually linked to the building model. Typically we use this form of detail to further refine the information present in the model with supplemental line-work on a 2D "detail". The detail is a viewpoint based on the model.
However, in AC17 - PBC or Priority Based Connections seems like it will help with detailing and eliminating some 2D line work.
For a more thorough discussion refer to to the AC Reference guide available under the Help menu.
Both Detail and Worksheet are 'linked' to the model - you can rebuild both. Worksheets can be boundary-less, i.e. takes a snapshot of the entire window. Details must have a boundary.
When Worksheets were first introduced (from memory), the existing Detail tool could not have a linked section marker or another detail marker placed in their window, but Worksheets could, allowing greater flexibility in reducing scale/cross referencing. However, since then, the detail tool has been upgraded to match.
As far as I can tell, apart from that they are the same (there are other minor differences in the default settings). You would probably only use one over the other to further organise your project (similar to elevation v section).
Correct - the worksheet can be linked to a model view.
However, it is important to remember that the WS link is not at all like the link of a section or elevation view. The worksheet is linked to a model view, elevations and sections are linked to the model itself.
In an elevation or section it is possible to manipulate the original 3D elements - for example re-size a window in the elevation view or move a door or delete an object in either section or elevation view. The link between elevations/sections and the model is bidirectional. The worksheet is limited to a snapshot/capture of the model view.
Worksheet views do not the option for automatic updating (!), do not support 3D, are not bi-directional, and can cause confusion if one performs work in the WS view ("Where did my work go?"). How often have you heard that one? While the linked WS is a useful tool, I would urge caution in its introduction to new users.
Just to keep this topic relevant, I'd like to post this link to a related wish list item. The ability to use 3D elements (even if you can't view them in 3D) in Worksheets would provide a wide range of benefits, including wall and symbol legends, wall/roof/slab assembly details (that are perfectly synced to their composite), and visual Favorites. Currently, you can use Objects, but only their 2d view.
On the flip side, Details also need some individualization, especially the ability to drag and drop from one project to another! See this link.