I have both and experience sensory issues differently. The autistic sensory issues are definitely more significant and impactful. Like my brain just cannot process things once it gets overwhelmed, sometimes it's painful and feels like my head is going to burst. ADHD sensory issues are more attention based, so I don't get overwhelmed in the same way, just frustrated and less able to control my executive function. I can also get hyperfixated on a specific thing, whereas with autism it just becomes all one big overwhelming stream of data that I can't process.