Mugs are heavy, large glasses with handles that come in many sizes and shapes. The handles make these heavy glasses easy to pick up and set down. In Japanese, they are called jokki ( ジョッキ).
During Oktoberfest in Germany, beer is served in hefty one-liter mugs, called Maßkrug -- in Japanese, dai-jokki (大ジョッキ) --, and people have no fear in clanking them together during toasts.
A Stein (or tankard) is a variation on the Mug, made of stone, silver, porcelain, or glass. Steins are often very elaborately decorated. They may be fitted with a lid, supposedly to keep flies out of the beer.
Mugs may be used for any kind of lager beer, as well as doppelbock, porter, or Märzen.