Hi @gprime84 - To answer for best of my knowledge,
Bulk API is great for performing tasks that involve lots of records, such as loading data into your org for the first time which will be performing on every specific time. Also, the Bulk API provides programmatic access that lets you quickly load large data into AEP date lake. Batch API will collect the data over the period of specific time. Once the batch API's are being collected and then it will send for the further processing. To be precise, this batch API's have the bulk records and meant for large quantities of information that aren’t time-sensitive. In respective to AEP, it take some extra time for profile unification, visitor stitching for the batch API's.
Streaming API is a specialized API for setting up notifications that trigger when changes are made to your data (In other hands, whenever the data is being triggered from source - Website data will be getting triggered as soon as user visited the site). Streaming API lets you expose a near real-time/Real time stream of data from your source system to the AEP Data lake. Here, Data would be streaming continuously (per your latency) to the AEP system. To be precise, This stream API's is fast and is meant for information that’s needed immediately. In respective to AEP, profile unification, visitor stitching happens in real/ near real time.
