The first main difference is the type of meat.  An Irish stew uses lamb for the protein while beef is more commonly in a regular stew though in some instances other meats are used as well.  Of course in a vegan and vegetarian version of Irish vegetable stew there isn't meat in the recipe. The second difference is in the consistency.  An Irish stew has a broth that’s thin since no flour or cornstarch is added to make the sauce thicker while a regular stew has a thicker consistency because the meat is often coated with flour before searing.  Last, the color is a major difference.  An Irish stew is paler in color since the meat is not seared or browned and all that’s used for liquid is a simple broth compared with a regular stew which is often deep brown in color.