Both the Achilles RS-140 2011 and the Achilles RV-156 2008 are inflatable designs, both built in inflatable, so the buying decision usually comes down to a handful of practical questions: how many people are you putting on the water, how far do you trailer, and what does your tow vehicle weigh?
On paper these two are close siblings in the size department - Achilles RS-140 2011 at 14,0 ft versus Achilles RV-156 2008 at 15,0 ft. At 114 lbs and 165 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 Achilles RV-156 2008 is rated for 12 passengers, while the Achilles RS-140 2011 caps at 9. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Achilles RV-156 2008 could be the deciding factor.
The Achilles RS-140 2011 is an inflatable design - lighter, easier to store, and quicker to launch from a beach or dock without a slipway. The Achilles RV-156 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 RV-156 2008 if your priority is putting more people on the water - it handles 12 passengers and at 15,0 ft it has the deck room to back that rating up comfortably. The Achilles RS-140 2011 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 9 that costs less to run day-to-day.