The paper/poster(?) by Harker & Stone  kinda says it all when it comes to the question: what changed in the description of autism between the DSM-IV-TR and DSM-5? The added bonus of comparing the US IDEA (Individuals with Disabilities Education Act) description of autism with DSM-5 will, I assume, also be important to quite a few people not least when it comes to any further research which uses the datasets on numbers of cases for example (see here).
I have little more to say aside from reiterating what already appears to be happening when it comes to the use of the revised descriptions of autism - autism spectrum disorder - in DSM-5 on numbers being diagnosed (see here). That and the requirement for quite a bit more investigation on the social communication disorder (SCD) category  including what a diagnosis of SCD actually translates into in terms of services and provisions offered compared to a DSM-5 diagnosis of ASD...
 Harker CM. & Stone WL. Comparison of the Diagnostic Criteria for Autism Spectrum Disorder Across DSM-5, DSM-IV-TR, and the Individuals with Disabilities Act (IDEA)3 Definition of Autism.
 Norbury CF. Practitioner review: Social (pragmatic) communication disorder conceptualization, evidence and clinical implications. J Child Psychol Psychiatry. 2014 Mar;55(3):204-16.