the alfresco-content portlet shows predifined content FROM alfresco to the general portal-user (ie not user specific as in relative to logged in user)
the alfresco-portlets (my documents etc) will show the content specific to the user from the corresponding user-parameters within alfresco for the authenticated user.
I myself have not (yet) been able to get the latter portlets to work from within liferay. These portlets can be checked out logging in to alfresco and choosing them for display in 'my alfresco'. Pretty cool if this works in liferay and probably what you mean and need.
Hopefully someone else will address the issues with these portlets for alfresco 2.9 in combination with the latest liferay in a way like the excellent manual for 2.1 and 4.3 was written in the wiki…