Danke sehr

Hallo Mehrdad, i hope, that i can help you. "Speise" includes nearly everything, no specific food. But its also kind of a oldfashioned word, i don't remember the last time i used it. I will give you some examples, but mention that my english is not that good: Welche Speisen habt Ihr anzubieten? - Which food do you offer? (as a question in a restaurant) Was wollt ihr speisen? - What do you want to eat? (speise is written without capital so it is a verb) Mahlzeit is something more like a deep integrated food happening with your family or at work in your everyday life. "Mahlzeit!" is a common exclamation to celebrate the pause at work when they eat together. So that is just my short knowledge and i hope that i could help Aljoscha

Danke!

Speise is a general word for food, it is a bit old-fashioned and is not used in everyday conversations when talking about food. You would hear it for example in a commercial for dish washing liquid that gets rid of all left over food on plates and dishes. These stains of leftover food are called Speisereste. Mahlzeit means meal, and it is also what we use to say Enjoy your meal! Mahlzeit!