The word Namaz is a derivative of Persian Sanskrit words, usually synonyms with worship or bowing before fire 🔥- The origin of this word is from Zoroastrianism.
The word Salat is a Quranic term for connection or reconciliation process of mind, body and soul.
The main focus in namaz is on physical movement performed in a prescribed way plus facing towards stone cubical structure in city Mecca and uttering of verses from Quran and non Quranic sources. This is done only by those who called themselves followers of Islam religion.
Whereas Salat has a universal appeal, it is a connection with your consciousness [Rabb], we do not have to know or understand Arabic language. Connection [salat] requires intense thought process whereas namaz requires no understanding, only good memory to mug up few Arabic verses.
The only criteria for establishing salat is that we must be pure and focused plus liberate ourselves from all filthy thoughts (mushrik) that distract us from knowing our true purpose or aim. Salat is a conversation with ourselves in our own language in order to connect, gather, call, reconcile, kill or eliminate then harmonize all our thoughts for the purpose of achieving peace of mind, in Arabic we call it Islam. 🙏
The configuration of thoughts in Quranic parlance is called qaum (community which remains standstill but continuously work). When these thoughts assemble, become harmonious and synchronized together, this moment of interconnectedness is called Salati min yaumil Jumah in Quranic terminology where you are your own leader (Imam), accumulating your scattered thoughts together and leading yourself to Peace (Islam) while no diversion must entice you.