Since nobody else is answering…
DI is down imaging only, directly under the boat and Structure Scan will do both under and out to the sides (Humminbird’s version of StructureScan is Sidescan).
Both manufacturers make both types and it’s a Ford/Chevy argument as far as I’m concerned. I’ve owned both and would not feel at a disadvantage with either.
There are many small differences that could make you want one versus the other, for me personally, I liked the fact that Lowrance is best suited for my custom made DrDepth maps, I personally think Lowrance has a cleaner image, and I like the StructureMap feature.
If I were a walleye guy, which I’m not, you would find a Humminbird on my boat hooked up to the newest Minnkota iPilot and a Lakemaster map and I would be trolling the contours like crazy.
If I were rich I might buy Humminbird’s 360 imaging and probably never use it.
Anyway, if you want more detailed opinions from me , PM me and we can talk on the phone, too much detail to write about…