More differences
The 240 cockpit seats are on the sides, with only a lip of an inch or so on the floor going into the companionway to the stairs. The 23.5 has the bench seats wrap in a complete U in front of the companionway. I suppose some advantages to this on the 23.5:1) keeps water out of the cabin better (if you get swamped, or dump a bucket while mopping)2) the mainsheet U-bolt is here instead of on the cockpit floor. This gives an extra foot brace when heeled over for someone sitting near the bulkheads.3) people put travellers on this bench surface on the 23.5. On the 240 it would have to span the gap and seem to split the cockpit more.RickW mentioned a vent on the 240. My 23.5 has a vent into the aft berth, just forward of the starboard locker that holds the gas tank.The 240 has relocated the gas tank to the center. I don't know where the battery is. On my 23.5, the outboard, gas tank, battery and porta-potie are all on the starboard side. The port side has only the galley and the small water tank, which I never fill. As a result, my boat listed to starboard when sitting at the dock. To make it float level, I put several bags of kitty litter on the port side totalling 150 pounds.The 23.5 has a ridge down the cockpit floor centerline. This has a square hole to receive the cabin table leg for cockpit picnics. I think the 240 has a different mount for the table in the cockpit and below (on the bench walls). What I don't recall is if the ridge is still there on the 240. It is used as a foot brace. Without it, shorter people and kids likely couldn't reach their foot to the opposite bench because the cockpit is so wide. This could be an issue when heeled over.I haven't sailed in a 240 but I do know that it has more water ballast (I thought 1200 lbs vs 1000 lbs, but I can't verify that). Somebody mentioned that the sail area is less. Presumably the 240 could be considered less tender but sail trim skills can compensate for this to some degree.