What is the difference between the letters Sīn and Ṣād in terms of istiʿlāʾ (elevation) and iṭbāq (adhesion), and is iṭbāq sufficient in place of istiʿlāʾ?

The letter Saad (ص) is pronounced with Itbaq (الإطباق - tongue-to-palate adhesion) and Istila’ (الاستعلاء - elevation of the tongue), unlike the letter Seen (س) which is characterized by Istifal (الاستفال - lowering of the tongue) and Infitah (الانفتاح - separation of the tongue from the palate). Itbaq is the adhesion of the tongue to the upper palate when pronouncing the letter, causing the sound to become confined between them. All letters of Itbaq are also letters of Istila’, and they are more prominent in tafkheem (تفخيم - velarization/emphasis) than other letters of Istila’. Istila’ is the elevation of the tongue towards the upper palate when pronouncing the letters "khaṣ ṣagḥṭ qaẓ" (خص ضغط قظ).