Was ist die Flugnummer vs Wie lautet die Flugnummer

I have seen both sentences. When would you use “Wie lautet…” instead?
 

Hallo RexV!

Was ist and wie lautet have the same meaning. The only difference in this context is that lauten "to be / to read / to run (as a text)" is slightly more formal than sein "to be," and so you are less likely to use it or come across it in casual conversation.

Tschüss!

Liss

A quick follow-up question.

I have seen these two sentences “Wie lautet es mit dem Projekt”? and “Wie geht es dit dem Projekt?”.

Is it correct to say that they are basically the same, except that the first is more formal?
 

Hallo RexV!

These two example sentences are actually both incorrect. 

The first might be Wie lautet das Projekt? but this means "What is the project?"

The second should probably be Wie geht es dir mit dem Projekt? which means "How are you getting on with the project?"

So they are actually not interchangeable. 

Hoping this is helpful,

Liss