What is the main written and semantic difference between the Arabic phrase هٰذَا الرَّجُلُ and the sentence هٰذَا رَجُلٌ?

Rules and Practical Exercises for Demonstrative Phrases

• The first is incomplete because al- is present, while the second is a complete sentence because al- is absent
• Both are exactly the same incomplete phrase
• The first is a complete sentence, and the second is an incomplete phrase