You can adapt almost any kettlebell exercise to use with dumbbells. For a very few exercises -- such as Turkish get-ups -- there's no real difference in mechanics. That said, just because you can adapt some of the more dynamic exercises -- like swings or windmills -- to use with dumbbells doesn't mean you should, if there's any other option. A kettlebell's deliberately imbalanced weight and compact size both lend themselves to continuous, dynamic movements much better than a dumbbell's balanced weight and relative bulk.
Video of the Day
You can easily substitute dumbbells for kettlebells while doing Turkish get-ups. Because you keep the weight static overhead, the difference in balance has minimal impact. Dumbbells can also be used to perform snatches and cleans, especially if you just can't quite master the art of rotating the kettlebell into place without banging it against your forearm. Other dumbbell-friendly exercises commonly associated with kettlebells include farmer's walks and high pulls.
Kettlebells Are Better
Technically, you can do kettlebell standards like single- or double-arm swings and windmills with a dumbbell, too -- but you'd need to hold the dumbbell by one end to imitate the kettlebell's natural imbalance. Kettlebells are better suited to dynamic movement -- so whenever possible, use a kettlebell for exercises that involve dynamic movement.