The Main difference between potato varieties is in the texture when cooked. Most varieties fall into either the "floury" or "waxy" category, although many potatoes are often described as "all rounders" which means that they are not overly floury or waxy, so are suited to a variety of cooking styles.
"Waxy" potatoes are also referred to as boiling, or new potatoes, and have less starch and a higher moisture content, making them suitable for salads, stews, soups, and any dish where you want the cooked potato to retain their shape. Usually they have thin delicate skins. They can be difficult to mash, and you can end up with a lumpy gluey mess.
"Floury" potatoes are often referred to as baking potatoes or old potatoes. Floury potatoes have a lower moisture content and a fluffy texture when cooked which makes them excellent for baking, mashing, and frying. Most 'old' potatoes are floury. Because of their high starch content, they fluff up beautifully when baked in their skins or mashed. They tend to yield up starch when boiled or fried, so should not be used for chips or salads without first being soaked.
Choosing potatoes: Choose potatoes that are firm and without sprouting eyes, and avoid those with any black or green dis-colouration. Potatoes that have been pre-washed are easier to prepare, but they do not store as well as those with a little earth left on them. (Also remember that not all soil "sticks" to potatoes, so those that look cleaner may just have been grown in a lighter, more sandy soil. Sprouted or soft potatoes are not toxic, but lack the nutrients of fresh potatoes.
Storing potatoes: Organic potatoes store well if kept in a cool, DRY place away from LIGHT. Never keep potatoes in the fridge, as the moist air will turn the starch into sugar. Avoid storing onions with potatoes, as this can make them rot. Avoid washing potatoes before storage, and keep them in something like a brown paper bag, or a cardboard box, anything with air flow. (Never store them in a plastic bag.)
Desiree: Oval, smooth red skin with pale yellow flesh. Holds shape well, excellent boiled for salad, good for dry roasting (baking) and mash. Not recommended for frying. Origin - Netherlands, now one of the most popular red skinned varieties.
Dutch Cream: large, oval shape, with yellow waxy flesh. Excellent for mash (all you need is a little salt) Excellent for purees and soup, the flesh is buttery and rich. Also makes a great roasted potato, and is well worth trying for its delicious taste. A high class potato!
King Edward: Round to oval shape, smooth pale skin with pink markings with creamy white flesh. Great for dry baking and roasting, good for mash, but not recommended for salad or frying. Originating in the UK this floury potato was one of the most popular varieties of the 20th century.
Kipfler: Cigar or finger shaped potato, often quite knobbly. Yellow skin with light waxy yellow flesh. Excellent for salad, or steam for use on pizza or foccacia. Good for boiling or roasting but not recomended for frying or chips. Originating in Austria, the kipfler potato has a wonderful buttery nutty taste, and is fast becoming a gourmet favourite in Australia.
Nicola: Long to oval shape with a rich yellow skin and yellow waxy flesh. Excellent as a salad or boiling potato, wonderful for mash. good for dry baking or roasting, Not recommended for frying. The taste of organic Nicola potatoes is simply delicious with a sweet nutty taste, and is a favourite with children. Also excellent for gratins and baked potato dishes. Originally from West Germany, now widely grown around the world.
Sebago: Long to oval shape, with white flesh and white skin. The sebago is a great all rounder, suitable for boiling, mash, roasting or baking. Good for chips, and mash, the sebago is a great all rounder. Originating in USA, the sebago is now widely grown in Australia, and is a variety commonly sold in supermarkets.