Non-stock is a setting that defaults how demand for that part is fulfilled.
If the part is placed on a sales order, it will be flagged to either be make to order or bought to order.
When a non-stock is placed on a bill of material and is not pull as assembly, it is make to job or buy direct to the job.
When the part is placed on a bill of material it will default to be pull as assembly if it is a manufactured part and it will come into a job as a subassembly.
Non-stock does not limit you from placing excess parts into inventory, but they typically do not go through inventory.
Note that a part on the fly also works just like Non-stock except for the fact that they cannot be be on a engineered BOM or placed into inventory.
Lastly, for a part to be a phantom BOM, it needs to be a Non-stock item.