In my opinion,Chinese is quite different from English.Difference from English ,in the Chinese we often put the key words at the end of the sentence which was from our English teacher. So in the first sentence ,the key word is 盖碗.Then ,If the speaker is a native Chinese,he will explain what is 盖碗 to you.But ,in the second sentence mostly from he who is interested in the meaning of the 盖碗. If you want more information,let me give you example, If I am writing an article,I will introduce more anout the 盖碗.My point is 盖碗. When I am asking a question,I will be more focused on 什么.So if we are asking the others about what,we will mostly use the second one. By the way I am learning translation. Hope to be useful to you. :D

лучше использовать номер два 盖碗 是 什么?

Yep,both right.But native speaker normally use the second sentence cuz there are some difference between Chinese and English ,For e.g:English question use"what's your name",you put "what"at first.So that's the reason.

我还真不知道

Thanx!