The Achilles RS-156 2013 is an inflatable design and the Achilles SU-14 2008 is a rigid inflatable design, so you're likely deciding between two noticeably different on-water experiences. Hull type shapes everything from ride quality and fuel burn to dock handling and resale trajectory.
On paper these two are close siblings in the size department - Achilles RS-156 2013 at 15,5 ft versus Achilles SU-14 2008 at 14,0 ft. Weight tells a clearer story for trailering families: the Achilles SU-14 2008 tips the scales at 280 lbs - 128 lbs less than the Achilles RS-156 2013 at 152 lbs. That difference is meaningful if you're working within a half-ton or three-quarter-ton truck's tow rating, especially once you factor in a motor, gear, and fuel.
The Achilles SU-14 2008 tops out at 55 hp. Engine specs for the Achilles RS-156 2013 aren't listed - confirm with a dealer before selecting an outboard.
For family outings this is probably the sharpest distinction between the two. The Achilles RS-156 2013 is rated for 12 passengers, while the Achilles SU-14 2008 caps at 6. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Achilles RS-156 2013 could be the deciding factor.
The Achilles RS-156 2013 is an inflatable design - lighter, easier to store, and quicker to launch from a beach or dock without a slipway. The Achilles SU-14 2008 is a rigid hull, which typically offers a more confident ride in chop and easier maintenance over the long term.
Bottom line: Choose the Achilles RS-156 2013 if your priority is putting more people on the water - it handles 12 passengers and at 15,5 ft it has the deck room to back that rating up comfortably. The Achilles SU-14 2008 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 6 that costs less to run day-to-day.