The exercise technique will be the same no matter what you're holding. It's even the same if you're performing the exercise empty handed. The biggest difference between using a dumbbell or kettlebell is that the kettlebell's odd shape will shift the weight's center of gravity "behind" your shoulder, so you'll need to work even harder to maintain a vertical arm position. That's why a kettlebell will feel more challenging than a dumbbell of the same weight. For example, if you're able to use a 30-pound dumbbell, you might struggle to control a 30-pound kettlebell. However, either can be effective for the exercise. Use whatever you have available and progress according to your capability.