The way I see it, there are a few issues that keep coming up whenever people compare resorts.
Size: The units at OKW are larger than the units at the VWL.
The 2 bedroom unit at OKW is 1322 sq ft while the units at VWL are 1080 sq ft. The difference in room sizes is made up primarily in the kitchen/livingroom/dining room area (the bedrooms are about the same size in both places). Besides giving you a larger living area, you also get a full size washer and dryer at OKW vs. a stacked set at VWL and the jacuzzi tub is larger at OKW (easily fitting 2 whereas at VWL 2 is a bit more of a squeeze, but still doable.

) The balconies are also smaller in VWL while OKW has something that might better be described as a patio or a deck.
Location: The VWL are located near the MK and you can get there by boat. In addition you're close to the activities at Ft. Wilderness. OKW isn't located near any major park, but it is located near Downtown Disney and you can take a boat there.
Transportation: Besides the afore mentioned boats, both of these resorts are served by buses. OKW is HUGE and spread out so there is an internal bus to facilitate getting to the pool or the restaurant. VWL is much more compact and the villas are actually VERY conveniently located to the bus stop (it's on the way to the main building).
Theming/Ambiance: So far I've tried to remain fairly impartial about my descriptions, but hands down VWL has some of the best theming on property. I've heard that OKW is themed like "key west" (imagine that, given the name!) but to me it has always seemed to not have much theming at all. Take a look at some pictures of the two to see what I mean. The "styles" of the two resorts are different as well... as I said, OKW is spread out and is more of a "condo" style while VWL is more like a hotel style that has all of the in-room amenities the condos at OKW.
Parking: At OKW you can park near your unit. At VWL, parking can be a bit further away, or you can choose to valet park (now $6/day if you do that).
Pools: I haven't ever been to the OKW pool, but the theming at the VWL pool is GORGEOUS. The hottubs are supposed to be some of the best on property (They're the best I've found). The OKW pool does not have a slide while the VWL pool does. I'm not saying that the OKW pool isn't gorgeous since I haven't ever been there.
Restaurants: OKW has one restaurant, Olivias and a few "snack bar" type places. VWL has 3 places to eat with 3 levels of formality. Roaring Forks is the "counter service" place. Whispering Canyon is the more family oriented restaurant. Artist point is the more expensive, gourmet, adult oriented restaurant. I'm not sure how the choices in the OKW snack bar type places compare to the choices in Roaring Forks.
Room Service: OKW shares room service with the moderates (port orleans), therefore it is limited to pizza and sandwiches. VWL shares room service with the deluxe WL, and has much more traditional room service offerings that you'd expect to find at a deluxe level hotel (they have breakfast, lunch and dinner and selections range from something like a family fried chicken bucket to more gourmet selections from Artist Point.)
Refillable Mug Program: I think at OKW you can buy a mug for $4.50 and subsequent refills cost $1.50. At VWL you can purchase a mug for $9 or $10 (depending on size) and subsequent refills are free.
Hope that helps!