Sensory processing disorder may resemble autism, but is a completely different disorder.
However, Sensory processing disorder differs from Autism in several ways. Most key is that Autism is a developmental disorder that has other symptoms related to social skills and obsessive interests. Meanwhile, SPD is a sensory disorder, only affecting reactions to sensory stimuli. One of the reasons the two disorders may be thought to be connected is that many with Autism have SPD. Conversely only a few people with SPD have Autism.