The Odyssey Lextra 2115L 2005 vs Odyssey Millennium 2103M 2004 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.
On paper these two are close siblings in the size department - Odyssey Lextra 2115L 2005 at 20,0 ft versus Odyssey Millennium 2103M 2004 at 20,0 ft. At 1 900 lbs and 1 850 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 2103M 2004 is rated for 13 passengers, while the Odyssey Lextra 2115L 2005 caps at 12. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Odyssey Millennium 2103M 2004 could be the deciding factor.
Bottom line: Choose the Odyssey Millennium 2103M 2004 if your priority is putting more people on the water - it handles 13 passengers and at 20,0 ft it has the deck room to back that rating up comfortably. The Odyssey Lextra 2115L 2005 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 12 that costs less to run day-to-day.