Methods and systems for multi-device, multi-channel cloud-based differential data synchronization. The system includes a server system, a source device including a first migration application instance, the source device configured to execute the first migration application instance to initiate a data transfer process with the server system to transfer user data to the server system upon a user ordering a target device, and the target device including a second migration application instance, the target device configured to execute the second migration application instance to initiate a data transfer process with the server system to transfer the user data to the target device, and execute a second data transfer with the source device to finalize data synchronization when the user is picking up the target device.