I think the terminology -- Czech, Polish, European, etc. -- can get confusing. In George Daniels book "Dynamic Nymphing, he shows a variety of nymphs that are useful for this style. There are "grubs" or caddis larva like flies, as well as mayfly nymphs, worms, scuds, and others.
To me, a Czech style nymph is simply one that is tied to sink fast. It is usually tied with heavy weight such as a tungsten bead, usually tied thin / sparse to facilitate sinking, and frequently has a hot spot. I see it as a tying style that is used to compliment the fishing style.