The main difference between dumbbell and kettlebell is the shape of the tool.
Dumbbells consist of a short bar with weights at each end, while kettlebells resemble cannonballs with handles. This difference affects how you use it by changing the weight distribution of each tool.
When you hold a dumbbell, your center of gravity is in the center of your palm, between the two ends of the weight, but when you hold a kettlebell handle, your center of gravity is in the larger part. It is usually a bell under the palm.
As you lift the kettlebell, this center of mass moves based on how fast you move and how the bell moves around your hand. These small changes change the way our muscles, fascia, and even the nervous system adapt to the movements being performed.
Each tool has its ideal use, but in general, kettlebells and dumbbells are interchangeable. The workout is likely to feel different with kettlebells and dumbbells. Some exercises may feel more difficult.
Take the dumbbell shoulder press exercise as an example. Press the dumbbell overhead so the weight is centered in your palm. But when you swap dumbbells for kettlebells, the weight is concentrated under your palms, on the outside of your wrists and forearms. This change can make it harder for your body to move the kettlebell.
That said, some people find kettlebells more comfortable than dumbbells for certain exercises. “I've worked with people who strain their wrists when holding dumbbells for goblet squats but feel no pain when holding the horns of a kettlebell in the same position.
Dumbbells are generally a better choice for hypertrophy (muscle strengthening) exercises and specific strength exercises. First of all, many people find dumbbells easier to hold. Many exercisers tend to be more comfortable with dumbbells for pressing exercises because they make it easier to maintain a neutral wrist position where the wrists are kept straight. Kettlebells, on the other hand, tend to pull the wrist back because of the weight distribution. Dumbbells are also often easier to maneuver for traditional bodybuilding moves or exercises that focus on specific muscle groups, such as triceps extensions, biceps curls, side raises and chest flies.
It's usually better to have two, but if you're considering one, dumbbells might be your best bet.