All of the following was quoted from “In Sheep's Clothing"
Rambouillet
This breed takes its name from the estate of King Louis the XVI at Rambouillet France, where in 1786 a flock of pure Spanish Merinos was established. After careful selection and breeding with other Merino flocks, the Rambouillet breed because a distinct entity. They were introduces to the United States from the French royal flock, and they became the foundation of most of the United States' western range breeds. Rambouillets are large, rugged, and smooth bodied, and moderately fast growing. Most rams have spiral horns, but there are also polled strains. They are gregarious as well as adaptable foragers, and they thrive in arid conditions. Although they have acceptable meat quality, Rambouillets are raised primarily for their high-quality fine wool. The fleece is very soft and has pronounced though slightly disorganized crimp, which gives it extremely good elasticity and excellent loft. The short staples are rectangular and have square, often dirty tips. Rambouillet wool can be used for baby wear and next to the skin knitted of woven fabrics, as well as blending with fine exotic fibers. While not as lustrous as Merino, it is more elastic and loftier. It is a good choice when these qualities are of paramount importance.
Targhee
The Targhee was developed by the United States Department of Agriculture as a dual-purpose sheep adapted to the dry western rangelands. The foundation of the breed was a cross of Rambouillet rams and Corriedale X Lincoln/Rambouillet ewes. Targhees are raised both for cross breeding and other meat breeds for market lamb production and for high quality apparel wool. Targhees are moderate-sized, polled sheep with open white faces. The fleece is fine and dense with very good loft, indistinct but well developed crimp, and short staple length. The staples are blocky in shape, with almost no luster. The extraordinary loft and elasticity of Targhee make it particularly suitable for fine, light, knitted and woven fabrics with good shape retention and crease resistance. In blends with other short fibers, Targhee adds loft and elasticity.