HDS10 the sonar has better clarity when fishing deep water like jigging spoons off shore in thr winter, Lowrance structure scan has 3 crystal receiver witch makes it digital and the Hummingbird has 2 crystal receiver which is anolog ( unless they have changed it in 2011) so the picture will be better on the Lowrance unit. I think the Lowrance units are easier to use, I have a 10 & 8 on my boat. Both are good unit, both have good pionts and bad, but thats my 2 cents.Gary