The Odyssey Millennium 2310M 2005 vs Odyssey Millennium II 2105M2 2005 comparison sits squarely in the category of decisions where specs alone won't tell the whole story — intended use, storage, and long-term ownership costs all factor in.
Size is the most obvious dividing line here. The Odyssey Millennium 2310M 2005 measures 22,0 feet overall (2005), giving it roughly 20,0 additional feet of deck space compared to the Odyssey Millennium II 2105M2 2005 at 2,0 feet (2005). At 205 lbs and 175 lbs respectively, both sit in a similar weight class — either should pair comfortably with most mid-size SUVs and half-ton trucks, though always confirm your specific tow rating with the motor added.
For family outings this is probably the sharpest distinction between the two. The Odyssey Millennium II 2105M2 2005 is rated for 14 passengers, while the Odyssey Millennium 2310M 2005 caps at 13. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Odyssey Millennium II 2105M2 2005 could be the deciding factor.
Bottom line: Choose the Odyssey Millennium II 2105M2 2005 if your priority is putting more people on the water — it handles 14 passengers and at 2,0 ft it has the deck room to back that rating up comfortably. The Odyssey Millennium 2310M 2005 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 13 that costs less to run day-to-day.