[threedaymonk]

That's just the convention in how words are presented to learners in different languages, I think, and it's surely obvious to anyone with even a few minutes of exposure to Romanian that -ul is one of the enclitics for the definite article.

Anyway, I don't know that's even a useful distinction on its own. The difference between "the X" and "X" doesn't map very well across languages, even within Europe. English drops the article in many circumstances in which Romance languages use it.