I have one ds with a dx of HFA and one ds with a dx of AS.
At the time of dx the main difference between the two boys was language development and the social side of things. Ds1 (HFA) had little or no language until he was 3ish whereas ds2 (AS) had a few words. Ds1 had no particular interest in other people at all whereas ds2 seemed to get that people were not just walking objects.
Fastforward a few years and it's a very different picture:
My HFA 10yr-old has very good language skills, so much so that most people who know him now would find it almost impossible to believe that he ever needed SALT. My AS 7yr-old still has language issues and often sounds like someone who has learnt English as a second language - quite formal, a little old-fashioned and takes things literally.
The ds with HFA now has a little group of friends, although he's still quite happy to be by himself. The ds with AS also has friends but doesn't really get the 'rules' of friendship.
So far no-one has mentioned changing my HFA ds' dx. The Paed still finds my ds with AS something of a puzzle though and has looked into other diagnoses for him.
Both boys are bright but are still classed as having learning difficulties. This is because aspects of their HFA/AS have made it harder for them to learn than for other NT children.
Ds1 has problems with co-ordination, motor skills and organisational skills which all have an impact on how he learns. He gets good results at school but it's more of a challenge for him.
Ds2's difficulties are related to auditory processing (making understanding instructions and tasks an issue which impacts on his ability to learn), sensory issues and the fact that he finds the world a generally confusing place to be.