What is the difference between org.apache.cxf and org.apache.cxf.impl modules in EAP 6.0.1

Issue

• Starting with EAP 6.0.1, cxf modules are split into 2 modules : org.apache.cxf and org.apache.cxf.impl.
• Which module to use and where ?
• While executing an application that uses Spring 3.x, the following exception is encountered,
• Why am I getting java.lang.ClassNotFoundException: org.apache.cxf.interceptor.security.SimpleAuthorizingInterceptor running a CXF project?

 java.io.FileNotFoundException: class path resource [META-INF/cxf/cxf.xml] cannot be opened because it does not exist

• I'm getting java.lang.ClassNotFoundException: org.apache.cxf.ws.security.wss4j.WSS4JOutInterceptor