As-Suhayili mentioned the dispute among the scholars over whether the Ruh is the same as the Nafs, or something different. He stated that it is light and soft, like air, flowing through the body like water through the veins of a tree. He states that the Ruh which the angel breathes into the fetus is the Nafs, provided that it joins the body and acquires certain qualities because of it, whether good or bad.
— Excerpt from: Tafsir Ibn Kathir -> Surah Al-Isra' -> The Ruh and the Nafs

♦ Difference between:

Nafs/Soul https://legacy.quran.com/91/7-10 & http://al-Quran.info/29/57/NG

AND

Ruh/Spirit http://al-Quran.info/17/85/Nw & http://al-Quran.info/17/85/N3

• the Ruh which the Angel puts into the fetus is called Nafs/Ruh-e-insani http://al-Quran.info/32/9/N8 & http://al-Quran.info/15/29/N8 that detaches from human body at the time of death http://al-Quran.info/6/61/N2 After that it lives in the realm of barzakh according to the life spent in this world https://legacy.quran.com/56/60-62

• the Ruh that descends only on prophets and messengers of Allah, that is the supportive Ruh, the Ruh for the inspiration on their Nafs http://al-Quran.info/40/15 It neither lives in their bodies nor lives in the realm of barzakh http://al-Quran.info/97/4 but sometimes possesses their bodies http://al-Quran.info/5/110 to prepare/make them perform certain task along with their physical bodies, for example: once Prophet Muhammad ﷺ was possessed by the Ruh, so that the Angels descended to take him for the journey of "Mairaj" http://al-Quran.info/70/4