1. Deployment Model: AWS Greengrass allows you to run AWS Lambda functions and keep device data in sync with AWS IoT Core while offline. On the other hand, AWS IoT Device Management is focused on managing the lifecycle of IoT devices such as onboarding, organizing, monitoring, and remotely updating devices.

2. Functionality: AWS Greengrass provides local compute, messaging, data caching, and synchronization services for connected devices. In contrast, AWS IoT Device Management focuses on managing fleets of devices at scale, offering features such as device registration, monitoring, and remote management.

3. Integration with Other Services: AWS Greengrass integrates seamlessly with other AWS services like Amazon S3, AWS Lambda, and Amazon Kinesis. AWS IoT Device Management, on the other hand, is tightly integrated with AWS IoT Core and provides device management capabilities specific to IoT devices.

4. Offline Capabilities: AWS Greengrass enables devices to operate locally with reduced latency and provides a seamless experience when connection to the cloud is intermittent. AWS IoT Device Management primarily relies on a cloud-based approach for device management tasks.

5. Edge Computing Focus: AWS Greengrass is designed for edge computing scenarios where data processing and analysis are performed closer to the data source. AWS IoT Device Management, on the other hand, focuses on centralized device management from the cloud.

6. Target Use Cases: AWS Greengrass is suitable for scenarios where low latency, offline operation, and local computation are essential, such as industrial automation and smart homes. AWS IoT Device Management is more relevant for managing large fleets of IoT devices efficiently, ensuring their security and compliance.

In Summary, AWS Greengrass focuses on enabling edge computing capabilities for IoT devices with offline operation, while AWS IoT Device Management is tailored for managing fleets of IoT devices efficiently from the cloud.