Why does the autism logo keep changing? & what is it?

Hi I thought I would start this thread because I am getting a tattoo of the autism logo, and on searching I found there are a few so which is the real logo? For many years it was the puzzle piece which I see most of, but the National autistic society logo is different and they sell pins and badges with the purple and pink logo on this site, then there is the autism awareness which is a ribbon with the puzzle piece pattern, IV seen butterflies, trees, and I’m a little lost, which is it?