It is recommended to use a Dialog Manager API Key to access the Dialog Manager API. A DM API key has the prefix VF.DM. and it provides the most up-to-date features such as version aliasing.
For backwards compatibility reasons, the DM API key accepts Workspace API keys (VF.WS) and legacy Workspace API keys (VF.). However, the usage of Workspace keys with the DM API key is considered deprecated behaviour.
Workspace API keys are unable to resolve version aliases, i.e, passing a string like 'development' or 'production' into the versionID parameter of DM API endpoints. You would need to provide an explicit version ID, which is harmful for maintainability, because each time your Voiceflow app updates a version, you must manually update to the newest version's ID in your Voiceflow integration.