Windrunner and windbreaker typically refer to the same thing - a thin coat (a lighter version of a jacket) designed to resist wind chill and light rain, with windbreaker being the generic term to refer to all products of this type and windrunner being associated to Nike's iconic jacket. See The Nike Windrunner: A Visual History.
Windrunner/windbreaker jackets are used in most athletic activities, made primarily of wind resistant and breathable nylon or similar lightweight material. Their single layer construction makes them cheaper, lighter weight, more compact, and potentially allows greater breathability by easier air and vapor transfer.
Constructed of only a single layer of fabric, windbreakers do not contain a waterproof membrane like their heavier duty counterparts. This means that in theory, they would get soaked by even the slightest amount of rain.
To combat this, manufacturers applied a DWR coating to the outside of all but one of the jackets that we tested. DWR coatings are important for two reasons. First off, they cause water to bead up and fall off a fabric, rather than soak in. This is what is meant by water resistant. Secondly, they help a fabric to breathe by keeping it dry. If a fabric is soaked through, it cannot allow water vapor to pass from the inside to the outside, and breathing is effectively stopped.
Know more about this apparel by reading OutdoorGearLab.com's how to choose the best wind breaker jacket.
Staying warm and comfortable while Nordic or backcountry skiing, snowshoeing, or hiking in winter is a constant challenge—we sweat, our bodies and clothes get damp, then we get cold. But it’s not impossible.
Check out these 12 pro tips for staying warm outdoors in winter shared by The Big Outside.