What is the difference between Ijma' (consensus) and Qiyas (analogical reasoning), with illustrative examples from the Prophetic era and contemporary reality?

Consensus (Ijma') and Analogical Deduction (Qiyas) are among the legal proofs (adillah shar'iyyah). Consensus (Ijma') is the agreement of all the mujtahids (qualified jurists) of the Muslim nation after the death of the Prophet Muhammad on a matter. It is a legal proof based on the infallibility of the Ummah from error, and its standing is after the Qur'an and the Sunnah. Examples include the prohibition of building churches in Muslim lands and the impermissibility of depicting prophets. As for Analogical Deduction (Qiyas), it is the application of a ruling from an original case (asl) to a new case (far') because of a common effective cause (illah) shared by both. Its standing is after Consensus (Ijma'). It consists of four pillars: the original case (asl), the new case (far'), the ruling (hukm), and the common effective cause (illah jami'ah). The Prophet Muhammad (peace be upon him) used it in his fatwas. Contemporary examples include analogizing DNA fingerprinting to 'qafah' (tracing lineage through physical resemblances) for determining paternity.