In the cited qualified account, what differentiates an explicit noun and a pronoun?

Fronting the Subject: Restriction, Reinforcement and the al-Jurjani–al-Sakkaki Debate

• An explicit noun always restricts while a pronoun always negates
• Both always convey exactly the same degree of restriction
• The explicit noun is assigned reinforcement; the pronoun can reinforce or restrict
• An explicit noun is an object and a pronoun necessarily an agent