Same areas of impairment, different manifestation.
In the realm of social impairment (there's a few other areas too):
Autism = socially aloof (ignores people; treats people as if they don't exist, etcetera, and with a lack and appreciation of nonverbal cues), or rarely, socially passive (lets people interact with her, but doesn't initiate anything; with all of the usual nonverbal cues lacking, of course)
Asperger's = socially odd (attempts to initiate social contact, but doesn't know how to do it, so appears odd, eccentric, rude, one-sided and verbose in many cases, etcetera, with a lack of the same nonverbal cues as in Autism), and socially pedantic/formal (constantly apologizes, whether it's needed or not, due to past failures in social interaction by saying the wrong thing; appears "calm and in control" oftentimes; sticks to social rules that she has learnt, and also lacks the usual nonverbal cues)
This above is taken from Wing's observations of a whole slew of children with an ASD (the lady who defined the current definition of AS); the aloof and passive groups tend to be labelled with Autism, and the odd/eccentric and stilted/formal groups tend to have the AS label.
The aloof group is the most common of all of them, and these individuals tend to have Kanner's Autism--as they develop, the picture tends to change in regards to the level of social and emotional aloofness, but it's usually always there to some extent, as social and emotional withdrawal are more common amongst adults with Autism compared to those with AS (I'm including social failures in as socialisation).