What is the difference between Autism and ADHD?

Why is Autism so hard to diagnose?

It can be difficult to tell the difference in some indiviuals.

My son has ADHD and my friends boy has aspergers. They are quite similar.

Many people with ADHD can have autistic traits and vice versa. Also, people with either conditions are likely to have other cobmorbid conditions such as ocd, tourettes, dyspraxia, anxiety and hypermobility syndrome.

It takes a competent professional to be able to pin point the exact cause of the behaviours.

ADHD is a developmental disorder that is characterized by a persistent pattern of impulsiveness and inattention with the component of hyperactivity. These symptoms need to be present before the age of 7 in order to be diagnosed with ADHD .
Autism is also a developmental disorder but one that is much more complex in nature affecting several areas of development. In order to be diagnosed with autism, a person must display significant/marked restriction in the areas of language/communication, social interaction and behaviour (stereotypical and repetitive). All symptoms need to be present by the age of 3 for this diagnosis.
Autism is harder to diagnose than ADHD because of the complexity of the disorder. It's possible for a person with autism at the extremely high functioning end of the spectrum to be improperly diagnosed with ADHD (which is why they usually explore that possibility when giving an ADHD diagnosis) but the reverse would be less likely unless there was some misunderstanding about a person's symptoms. When dealing with the more "classic" presentation of autism, the two disorders don't look the same at all. The only similarities they share is that those with autism tend to be impulsive, inattentive at times and some are/may appear to be hyperactive.

ADHD means Attention Deficit Hyperactivity Disorder. Which mean breaking it down that the person finds it difficult to concentrate on any thing for a long period of time. That they find it hard to pay attention to things. Hyperactivity Disorder means that they find it hard to stay still for long periods of time, They are always moving from one thing to another. They never stay in one place for more than a few minutes. Autism is something all together different Autistic kids have trouble forming bonds with others, They are sometimes unable to communitcate with others they might have developmental delays but most have high IQ's. They live in a world of their own and it's hard to break through to them.

ADHD is a disorder where the individual is hyper-active and cannot focus his/her attenion on a perticular objject for the normal length of time.

Autism is a disorder where the individual lacks the ability of empathizing with others. This may be as a result of lack of mirror neurons in the brain. Try to read about mirror neurons in order to know what exactly they are.

The difference is
ADHD contains concerntracion behavior and hypertivity and sometimes how fast you get pissed off
Autism is a brain development disorder which also effects concerntracion but the behavior reactions in autism is repetive behavior