American Potatoes vs. Spanish Potatoes
What are sometimes referred to as Idaho potatoes are generally russet potatoes, a variety of mealy potato commonly grown in Idaho. Mealy potatoes are one of the two broad categories of potatoes: Waxy and Mealy. Mealy potatoes are more dense, higher in starch and lower in sugar and moisture than waxy varieties. Mealy potatoes are used in dishes such as baked potatoes, mashed potatoes, and french fries as they maintain a lighter, mealy texture and don't brown too quickly. 

Waxy potatoes include most red skinned potatoes and are less dense with less starch and more sugar and moisture. Waxy potatoes maintain their shape better when boiled so are preferred for that preparation method as well as sauteing and roasting.

Some potatoes exist near the middle of these two extremes and are sometimes referred to as all-purpose potatoes as they will work in a wide variety of preparations. Yukon Golds are probably the most widely available example of all-purpose / medium density potatoes in the US.

There are a huge variety of potatoes grown throughout the world. The trick is to figure out if your senora's recipe requires mealy or waxy potatoes and then purchase the a variety from that category. If you don't know whether the variety in question is mealy or waxy you can check by placing the potato in a brine made of 1 part salt to 11 parts water. If the potato floats it is waxy, if it sinks it is mealy.