Kitchen islands and kitchen island carts are both good ways to increase work and counter space in a kitchen. They have butcher block or stainless steel cutting areas, extra drawers, storage cupboards, shelves, and other conveniences. They come in many designs and styles. They can be wood, sleek steel or brightly colored. Kitchen islands have become almost standard in house designs. An older kitchen with empty space in the middle can be greatly improved with a kitchen island or cart.
An island that is installed in one place is not just a work and storage space. Put a few chairs next to it, and it's an informal meal table. For entertaining, make it a buffet or a bar. Fixed islands can have electric outlets, sinks, even stove tops and ovens. These islands can be small kitchens all by themselves.
The advantage of a kitchen cart is that it moves. Mounted on wheels, a cart goes where it is needed. Cutting salad on a counter top but don't have anywhere for the big salad bowl? Bring the cart over. Take it to the sink to put clean dishes on. The disadvantage is that it can't have permanently installed power or appliances.