Workflow Engines vs. Orchestrator Skills: What Actually Sets Them Apart

A workflow engine is a program that holds a procedure and calls a coding agent only when intelligence is needed, inverting the traditional orchestrator model where the AI model itself drives the process. Unlike orchestrator skills, which store procedures as Markdown in a conversation session, workflow engines run procedures as validated programs in their own processes with persistent run state on disk. This architectural difference allows workflow engines to validate control flow at load time, catching errors like missing nodes before a run begins rather than mid-execution. Engines can also run independent steps in parallel by computing dependency layers, whereas orchestrator skills process phases serially due to their conversational nature. Platforms like Archon and Microsoft Conductor are cited as examples of this engine-based approach, though the article notes not all tools marketed as workflow engines truly qualify.