OK I am confused
Did Streamlight or Insight but the other?
Are they one and the same?
I am looking at the M6X weapons lights and have seen them in both the Steamlight and Insight name?
Are there any differences?
Insight makes tactical lights.
Streamlight started with utility lights and moved into some tactical stuff.
Because Streamlight had better internet and retail marketing, Insight let them start distributing their stuff. I haven't seen any of the M3/M6 stuff marked as "Streamlight", but I could be wrong.
Either way, it's the same light.