What is the difference between the words "al-Waahid" (the One) and "al-Ahad" (the One) in the Qur'an, as in His saying, the Almighty: (He is Allah, al-Waahid) and His saying, the Almighty: (Say: He is Allah, Ahad)?

Both "Al-Wahid" (The One) and "Al-Ahad" (The Unique/The One and Only) are among the beautiful names of Allah. "Al-Wahid" is the Singular Being who has always been alone, distinct in His essence, having no peer or similitude. As for "Al-Ahad," it is used to negate any associated number, being singular in meaning. It has also been said that Al-Wahid is He who does not divide, does not multiply, does not accept division, and has no peer or likeness.