There are two main classifications of kebab.  One is the shish kebab.  The other one is the doner kebab.  Now, both of them are entirely different from each other.  The doner kebab includes Shawarma and Gyros.  The cooking of meat on the vertical split is the common thing between these two. 

What is the difference between Shawarma and Gyros? 

The gyros are a Greek dish.  Usually, it includes the pork or lamb.  You may also get certain seasonings on top of it.  The seasonings include oregano, thyme, rosemary and marjoram.  It is ground into fine pieces into a loaf.  The garnishes include onion, tzatziki sauce, tomatoes, garlic yogurt with dill and cucumbers. 

But what about the Shawarma?  Well, in this case, the meat is the lamb, turkey or chicken.  It barely has a loaf, but chunks of meat in it.  The seasonings include cardamom, cloves, turmeric and cinnamon.  These also may have specific variations. 

Garnishing this dish is what is really unique.  It offers servings of tahini, hummus and sometimes pickles as well. 

So, both the dishes fall within the same category, but are still different.