Note: for easier comparison I have moved the seam and resteasy dirs into the jboss-as dir.
Please let me know if you need a more meaningful list (detailed diffs?, just a list of affected files inside a jar?).

Following jars are present in different locations and have different content. The first jar is the is the reference and has been compared with every other occurrence.

For example, activation.jar is present in 5 locations but only
jboss-as/lib/endorsed/activation.jar
and
jboss-as/client/activation.jar
have the same content. The other 3 jars located in
jboss-as/seam/lib/activation.jar
jboss-as/resteasy/lib/activation.jar
jboss-as/resteasy/resteasy-jaxrs.war/WEB-INF/lib/activation.jar
have different content when comparing with the first one (lib/endorsed).

Here's the complete list:

jboss-as/lib/endorsed/activation.jar
jboss-as/seam/lib/activation.jar

jboss-as/lib/endorsed/activation.jar
jboss-as/resteasy/lib/activation.jar

jboss-as/lib/endorsed/activation.jar
jboss-as/resteasy/resteasy-jaxrs.war/WEB-INF/lib/activation.jar

jboss-as/common/lib/antlr.jar
jboss-as/seam/lib/antlr.jar

jboss-as/common/lib/bsh.jar
jboss-as/seam/lib/gen/bsh.jar

jboss-as/common/lib/bsh.jar
jboss-as/seam/lib/bsh.jar

jboss-as/seam/lib/commons-codec.jar
jboss-as/resteasy/lib/commons-codec.jar

jboss-as/seam/lib/commons-codec.jar
jboss-as/resteasy/resteasy-jaxrs.war/WEB-INF/lib/commons-codec.jar

jboss-as/common/lib/commons-collections.jar
jboss-as/seam/lib/commons-collections.jar

jboss-as/seam/lib/commons-httpclient.jar
jboss-as/resteasy/lib/commons-httpclient.jar

jboss-as/common/lib/commons-logging.jar
jboss-as/seam/lib/commons-logging.jar

jboss-as/common/lib/commons-logging.jar
jboss-as/resteasy/lib/commons-logging.jar

jboss-as/lib/concurrent.jar
jboss-as/seam/lib/concurrent.jar

jboss-as/lib/dom4j.jar
jboss-as/seam/lib/dom4j.jar

jboss-as/common/lib/ejb3-persistence.jar
jboss-as/seam/lib/ejb3-persistence.jar

jboss-as/common/lib/el-api.jar
jboss-as/seam/lib/el-api.jar

jboss-as/server/production/deployers/jbossws.deployer/FastInfoset.jar
jboss-as/resteasy/lib/FastInfoset.jar

jboss-as/server/production/deployers/jbossws.deployer/FastInfoset.jar
jboss-as/resteasy/resteasy-jaxrs.war/WEB-INF/lib/FastInfoset.jar

jboss-as/common/lib/hibernate-annotations.jar
jboss-as/seam/lib/hibernate-annotations.jar

jboss-as/common/lib/hibernate-commons-annotations.jar
jboss-as/seam/lib/hibernate-commons-annotations.jar

jboss-as/common/lib/hibernate-entitymanager.jar
jboss-as/seam/lib/hibernate-entitymanager.jar

jboss-as/common/lib/hibernate-validator.jar
jboss-as/seam/lib/hibernate-validator.jar

jboss-as/common/lib/hsqldb.jar
jboss-as/seam/lib/hsqldb.jar

jboss-as/lib/javassist.jar
jboss-as/seam/lib/javassist.jar

jboss-as/lib/javassist.jar
jboss-as/resteasy/lib/javassist.jar

jboss-as/lib/javassist.jar
jboss-as/resteasy/resteasy-jaxrs.war/WEB-INF/lib/javassist.jar

jboss-as/lib/endorsed/jaxb-api.jar
jboss-as/seam/lib/jaxb-api.jar

jboss-as/lib/jaxb-impl.jar
jboss-as/resteasy/lib/jaxb-impl.jar

jboss-as/lib/jaxb-impl.jar
jboss-as/resteasy/resteasy-jaxrs.war/WEB-INF/lib/jaxb-impl.jar

jboss-as/server/production/lib/jbosscache-core.jar
jboss-as/seam/lib/jbosscache-core.jar

jboss-as/server/production/lib/jbosscache-core.jar
jboss-as/resteasy/lib/jbosscache-core.jar

jboss-as/lib/jboss-common-core.jar
jboss-as/seam/lib/jboss-common-core.jar

jboss-as/lib/jboss-deployers-client-spi.jar
jboss-as/seam/lib/jboss-deployers-client-spi.jar

jboss-as/lib/jboss-deployers-core-spi.jar
jboss-as/seam/lib/jboss-deployers-core-spi.jar

jboss-as/lib/jboss-jmx.jar
jboss-as/seam/lib/jboss-jmx.jar

jboss-as/server/production/deploy/jboss-local-jdbc.rar
jboss-as/seam/bootstrap/deploy/jboss-local-jdbc.rar

jboss-as/lib/jboss-logging-spi.jar
jboss-as/seam/lib/jboss-logging-spi.jar

jboss-as/lib/jboss-system.jar
jboss-as/seam/lib/jboss-system.jar

jboss-as/lib/jboss-vfs.jar
jboss-as/seam/lib/jboss-vfs.jar

jboss-as/server/production/deploy/jboss-xa-jdbc.rar
jboss-as/seam/bootstrap/deploy/jboss-xa-jdbc.rar

jboss-as/server/production/deploy/management/console-mgr.sar/jcommon.jar
jboss-as/seam/lib/jcommon.jar

jboss-as/server/production/deployers/jbossws.deployer/jettison.jar
jboss-as/resteasy/lib/jettison.jar

jboss-as/server/production/deployers/jbossws.deployer/jettison.jar
jboss-as/resteasy/resteasy-jaxrs.war/WEB-INF/lib/jettison.jar

jboss-as/server/production/deploy/management/console-mgr.sar/jfreechart.jar
jboss-as/seam/lib/jfreechart.jar

jboss-as/server/production/lib/jgroups.jar
jboss-as/seam/lib/jgroups.jar

jboss-as/server/production/lib/jgroups.jar
jboss-as/resteasy/lib/jgroups.jar

jboss-as/server/production/deploy/jms-ra.rar
jboss-as/seam/bootstrap/deploy/jms-ra.rar

jboss-as/server/production/deploy/jbossweb.sar/jsf-libs/jsf-api.jar
jboss-as/seam/lib/jsf-api.jar

jboss-as/server/production/deploy/jbossweb.sar/jsf-libs/jsf-impl.jar
jboss-as/seam/lib/jsf-impl.jar

jboss-as/common/lib/jsp-api.jar
jboss-as/seam/lib/jsp-api.jar

jboss-as/seam/lib/jsr250-api.jar
jboss-as/resteasy/lib/jsr250-api.jar

jboss-as/seam/lib/jsr250-api.jar
jboss-as/resteasy/resteasy-jaxrs.war/WEB-INF/lib/jsr250-api.jar

jboss-as/common/lib/log4j.jar
jboss-as/seam/lib/log4j.jar

jboss-as/common/lib/mail.jar
jboss-as/seam/lib/mail.jar

jboss-as/common/lib/mail.jar
jboss-as/resteasy/lib/mail.jar

jboss-as/common/lib/mail.jar
jboss-as/resteasy/resteasy-jaxrs.war/WEB-INF/lib/mail.jar

jboss-as/server/production/deploy/mail-ra.rar
jboss-as/seam/extras/mail-ra.rar

jboss-as/common/lib/quartz.jar
jboss-as/seam/lib/quartz.jar

jboss-as/common/lib/servlet-api.jar
jboss-as/seam/lib/servlet-api.jar

jboss-as/common/lib/slf4j-api.jar
jboss-as/seam/lib/slf4j-api.jar

jboss-as/common/lib/slf4j-api.jar
jboss-as/seam/lib/gen/slf4j-api.jar

jboss-as/common/lib/slf4j-api.jar
jboss-as/resteasy/lib/slf4j-api.jar

jboss-as/common/lib/slf4j-api.jar
jboss-as/resteasy/resteasy-jaxrs.war/WEB-INF/lib/slf4j-api.jar

jboss-as/lib/endorsed/stax-api.jar
jboss-as/seam/lib/stax-api.jar

jboss-as/lib/endorsed/xercesImpl.jar
jboss-as/seam/lib/xercesImpl.jar