souvlaki vs shish kebab

souvlaki and shish kebab both are nouns.

Word	Noun	Adjective	Verb	Adverb
souvlaki	Yes	No	No	No
shish kebab	Yes	No	No	No

As nouns, shish kebab is a hypernym of souvlaki; that is, shish kebab is a word with a broader meaning than souvlaki:

souvlaki: made of lamb
shish kebab: cubes of meat marinated and cooked on a skewer usually with vegetables

Other hypernyms of souvlaki include kabob, kebab.

souvlaki (noun)	shish kebab (noun)
made of lamb	cubes of meat marinated and cooked on a skewer usually with vegetables