My understanding is that the “Insight” feature includes more detailed navagation information on waters like the great lakes and coastal areas.
The base map is just general info. Most of what we would do here in the Midwest we can easily accomplish with a chip so the insight isn’t really worth the extra cost.
If you primarily fish the great lakes or coastal areas then it may be worth the extra $.
Once again..that is my understanding and the info I got when I bought my HDS10. I did not get the Insight model.