There has been a lot written about this topic, yet the question keeps appearing, mostly from those trying to make the choice. Having spent hundreds of hours in the Adventure and about 15 to 20 in the Revolution, I've had the good fortune to compare them with regard to speed, sailing, wake riding and side by side general handling characteristics. Of course, this is just one person's observations.
The Adventure is unique among all the Hobie kayaks in two respects. 1) It's the only one that has the capability for using the dagger-board (for sailing); and 2) It contains the built in hardware (2007 models and up) to be optionally converted to the Island sailing trimaran. Aside from that, The Adventure sits a little lower in the water. It weighs 4# more. Although they both are rated at 350# total carrying capacity, I am convinced that the Revo has more "reserve" capacity beyond that than the Adventure.
They look similar, but three factors provide very different handling between the two. Length, "rocker" and rudder placement make all the difference, as we shall see. Briefly, the Revo is about 2 1/2 feet shorter (1" wider), has a moderate amount of rocker (Adventure has virtually none) and the rudder is mounted slightly lower in the water.
Cockpit and deck plan:
The Adventure has a slightly longer and wider cockpit. It has two drink holders, both of which fully drain. With the longer bow, you can stow the paddle halves in the forward hatch. Only problem, you can't get to the forward hatch while underway without leaving the cockpit.
The Revo feels a little more cozy. There is only one drink holder which annoyingly does not drain fully and is so shallow that small bottled waters are always flopping out, forcing you to store them behind the seat area. Although you cannot fit the paddle in the forward hatch, you can access it fairly easily from the cockpit while underway.
On the water:
They both have very good stability, with primary stability being about equal but a slight edge to the Revo in secondary stability. This is not a critical issue by any means.
A big nod to the Revo here. It turns like a sports car while the Adventure turns like the Titanic by comparison. Like most kayaks, the Revo can accomplish minor course corrections simply by leaning away from the direction you want to turn. This doesn't work out quite so well with the Adventure -- you can lean till you fall out before any turning happens. The sailing rudder helps them both (and is recommended as an automatic upgrade), but much more so for the Adventure. It is practically a must for sailing and wake riding for either boat and will add a lot of sizzle to any handling situation.
They are both decent paddlers. The Adventure obviously tracks a little bit better, but the Revo is more sensitive to turning cues.
For me, the Adventure sprints (with Turbofins) about .6 or .7 MPH faster. A much more realistic figure though is cruise speed, where the difference narrows to about .3 to .4 MPH on a "high speed cruise" to about .2 to .3 MPH on a casual cruise. This all assumes flat water and light wind.
Wind and chop:
Both of the boats are very seaworthy. But there is a noticeable difference between the two in the manner that they behave in weather. The Adventure handles wind and chop with great ease -- it just cuts through it as if it were a minor annoyance. As a result, it is easier to go against weather, although you'll likely have a wetter ride in larger chop. The Revo has more buoyancy in the bow and tends to ride over the chop or pound against it. Next to the Adventure (which is in a class by itself here) the Revo is the next best in the Hobie line at handling weather and I would rate it as very good. You'll also come out drier with chop, especially on the beam.
A by-product of this is that the Adventure is faster in weather, so it has a greater range and is more comfortable in foul weather or unfriendly winds.
Upwind in small chop, the Adventure is very quiet, whereas the Revo experiences a little hull slap. Side by side, this difference is quite noticeable.
Both boats are lively and exciting to sail, although the majority would consider it a secondary activity -- most sailboats are faster (unless there's no wind). The Revo has the better sailing manners -- it has a better sheeting angle on the sail and its secondary stability and wider beam make it a little more stable. You can also "hike out" a bit more. On the other hand, It's easy to modify the sheeting angle on the Adventure, and it accepts the dagger-board for better upwind performance. The dagger-board also adds a stability factor to the Adventure that makes the handling of gusts and wind changes much easier than without.
For those who like to sail without all the excitement, the Sidekick (outrigger kit) makes for very stable sailing.
Boat wake rides:
(I don't think anybody really does these but me). This is an exciting and fun activity when you didn't bring your sail or there is no wind. You need ST or preferably Turbofins and a sailing rudder for either boat. Both boats can do it, but the Revolution will give you a better ride. Shorter, with a more buoyant bow and a more responsive helm, it's more likely to get on the swells rather than span them.
This is a bit risky, but I would characterize the Revolution as akin to a sports car or Steerman bi-plane -- fun, willing and playful. The Adventure by comparison, is more like a Cadillac or jet fighter -- smooth and deliberate.
So as you can see, they don't look that much different, but as you get to know them, the more subtle differences offer each advantages in different ways.