Job Server
The SAP BusinessObjects Data Services Job Server retrieves the job information from its respected repository and starts the data engine to process the job.
The Job Server can move data in either batch or real-time mode and uses distributed query optimization, multi-threading, in-memory caching, in-memory data transformations, and parallel processing to deliver high data throughput and scalability.
Access Server
The SAP BusinessObjects Data Services Access Server is a real-time, request-reply message broker that collects message requests, routes them to a real-time service, and delivers a message reply within a user-specified time frame.
SAP Basis Knowledgebase 