What is the difference between Furood (obligatory acts) and Arkaan (pillars), and is a Fard higher than a Wajib (necessary act) and cannot be compensated for by the prostration of forgetfulness (sujood as-sahw), like a “pillar”?

What is mentioned in the book, that an obligatory act (fard) is stronger than a necessary act (wajib), and that it is not compensated for by the prostration of forgetfulness (sujud al-sahw) if left out forgetfully, unlike a necessary act, is consistent with the Hanbali madhhab. The Hanbalis have given examples for the obligatory act (fard) with bowing (ruku') and prostration (sujud), and for the necessary act (wajib) with the first tashahhud and saying "Subhana Rabbiyal 'Azim" once in bowing, and "Subhana Rabbiyal A'la" once in prostration. The necessary act (wajib) according to the Hanbalis is what others refer to as an emphasized Sunnah (Sunnah mu'akkadah). As for "fard" (obligatory) and "rukn" (pillar), there is no difference between them. There is a well-known difference of opinion between the Hanafis and the majority (jumhur) regarding the issue of "fard" and "wajib". For the majority, "fard" and "wajib" are synonymous. However, the Hanafis hold that they are distinct; according to them, "fard" is what is established by definitive proof (dalil qat'i), while "wajib" is what is established by presumptive proof (dalil dhanni).