SCA ARCHITECTURE was followed in 11g and not in 10g
In 11g you can put all your project SOA components in composite.xml file and DEPLOY as a single deployment unit to single server, where in 10g you have to deploy each component to the respective server (i.e. ESB to ESB server, BPEL to BPEL Server)
Basically all the SOA components like BPEL, ESB (Called MEDIATOR in 11g), & OWSM are brought into one place in 11g using SCA composite concept.
The major difference between 10g & 11g would be the app server container. 10g by default runs onOC4J while 11g runs on Web logic Server.
In 10g every BPEL is a separate project, but in 11g several components can make 1 project as SCA.
In 10g consoles are separate for BPEL and ESB, but in 11g Enterprise Manager contains all.
In 10g BAM and BUSINESS rules are outside SOA SUITE, but in 11g they are in SOA Suite.