"Welcome! Thank you!"
Translation:Bun venit! Mulțumesc!
The course tries to make a differentiation in politeness. In Romanian, "mersi" is familiar, while "mulțumesc" is formal. Maybe you can't say that about the relation between "thanks" and "thank you" in general, seeing how English is spoken by a huge amount of people in a huge amount of places. But, as a foreigner learning English, it does feel like that to me.