Rutabaga is a hybrid of cabbage and turnip and is commonly called yellow turnip because of its yellow flesh. Both are root vegetables and turnip is colloquially called white turnip because its skin and flesh are both white.
Rutabagas are harvested at larger sizes while turnips are often harvested in smaller sized "baby" turnips.
Rutabaga has yellow flesh. It is a denser root and there are numerous side shoots. The leaves of rutabaga are waxy and smooth and grow from the part that protrudes above the ground. There is a distinct neck or visible crown in rutabagas. The vegetable is harvested at larger sizes.
Turnip has white skin and white flesh. The part that protrudes above the ground is slightly purple or greenish in color. Mostly, the root is conical in shape but occasional tomato shapes are also observed. There are no side roots in turnips. Turnip leaves are commonly eaten as turnip greens and are similar in flavor to mustard greens. Turnips are harvested at smaller sizes and baby turnips are a specialty. These come in yellow, red and orange fleshed varieties and can be eaten raw in salads.
Rutabaga is commonly roasted and served with meats, is an important ingredient of the Swede casserole, used as an enhancer in soups and salads, can be baked as well as boiled along with potatoes. Rutabagas can be peeled like potatoes prior to being cooked. Some of the dishes that use rutabagas are Rotmos, Smalahove, Raspeball, Potch. The Scots make an interesting dish of tatties and neeps which is potato and rutabagas mashed separately and served with haggis. Swedes are often mashed with carrots for a traditional Sunday roast. Rutabagas are parts of soups, stews, casseroles, baked pastry etc.
Turnip is used as a vegetable in salads, soups and casseroles. Larger varieties are used as fodder for farm animals. Turnips are used to flavor juice made from carrots and spices in Turkey. They are commonly used as pickles in Middle East. Turnip is attributed medicinal properties and is believed to reduce body temperature.
edit How to Grow Rutabagas and Turnips