Virtual business components (VBCs) are mechanisms in Siebel EAI by which data from an external system can be viewed in Siebel applications without having to replicate that data within the Siebel Database.
 VBCs are configured in Siebel Tools and use Business Services to access data from an external system. VBCs can use standard transports like MQSeries, HTTP, and MSMQ, along with the XML Gateway Service, to query, insert, and update data.

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1.  Based on Usage: DP is used to draw/pick a value for a field in Originating BC from any BC  whereas MVGs is an alternative to a detail view for managing parent and related child records. It allows complex queries that span multiple BCs