Locally managed gateways /clusters are possible in Spark only; It provides a simple and ... cheaper way to manage and monitor the gateways. Plus, there are SMB / SME unique features available when managed locally;
Locally managed gateways can be connected to Spark Management; It makes sense when multiple gateways are deployed
Centrally managed gateways, are more advanced by means of mainly security and networking features; This solution is considered enterprise-grade; Both SPARK and Quantum can be used for that matter
Please contact me directly if more clarification/assistance is needed
Amir