Apache NiFi and Streamsets are two open-source ETL tools that offer visual dataflow programming, allowing users to create programs without writing code. Both tools have their pros and cons, with Apache NiFi having a clean architecture but a spartan user interface, while Streamsets has a more attractive UI but can be less user-friendly due to its validation requirements. Data Provenance is a feature in Apache NiFi that records the history of data flows, which can be useful for debugging purposes. Both tools have similar functionality and are suitable for record-based data and streaming. Ultimately, the choice between Apache NiFi and Streamsets depends on individual preferences and needs, with live monitoring being a key feature in Streamsets that sets it apart from Apache NiFi.