supply chain vs value chain

Very different, actually. Value chain is the Porter model of primary activities (inbound logistics, etc) and support activities (firm infrastructure etc). Supply chain is the process by which a company obtains raw materials and components and distributes finished products. See here: https://www.accaglobal.com/uk/en/student/exam-support-resources/professional-exams-study-resources/p3/technical-articles/value-chains.html