Story started around 2012 with S&OP Hana until version 3.0. Following marketing definition and Gartner group vocabulary, this application has now change its name to IBP S&OP 4.0. Nothing changes within S&OP except improvements with 4.0.
IBP is a new family of application in SCM under Hana
BCP belongs to analytic family, not much appropriate for SCM Concern.
APO is the previous APS of SAP that is still supported until 2025. Say a new customer needs SCM advance planning, better going IBP nowaday but nothing wrong with APO neither
Daniel