Classic data integration: Asynchronous,
Classic data integration provides asynchronous and uni-directional data synchronization experience between model-driven applications in Dynamics 365 and Dynamics 365 Finance and Operations applications. It's an IT-administrator led experience and you must schedule the data sync jobs to run on a specific cadence. Classic data integration is suitable for business scenarios that involves bulk ingress/egress of data across Dynamics
365 applications.
Note: Dual-write: Synchronous, Bi-directional.
Dual-write provides synchronous, bi-directional, near-real time experience between model-driven applications in Dynamics 365 and Finance and Operations applications. Data synchronization happens with little or no intervention and is triggered by create, update and delete actions on an entity. Dual-write is suitable for interactive business scenarios that span across Dynamics 365 applications.