1. Integration with Ecosystem: Amazon Machine Learning is well-integrated with AWS ecosystem, allowing seamless access to other AWS services for data storage and processing. On the other hand, Firebase Predictions is closely integrated with Google Cloud Platform, providing similar advantages within the Google ecosystem.

2. Model Training: Amazon Machine Learning uses a supervised learning approach where users need to upload labeled data for training models, while Firebase Predictions leverages unsupervised learning techniques, enabling predictions without the need for pre-existing labeled datasets.

3. Scalability: Amazon Machine Learning offers flexibility in scaling resources up or down based on demand, suitable for projects with varying computational needs. Firebase Predictions automatically scales resources to manage fluctuating workloads more dynamically, making it ideal for rapidly changing requirements.

4. Customization: Amazon Machine Learning allows extensive customization options and fine-tuning of models to cater to specific use cases, providing a high degree of control over the prediction process. In contrast, Firebase Predictions offers simplified, user-friendly interfaces and pre-built models, making it easier to deploy predictions quickly without intricate customization.

5. Supported Platforms: Amazon Machine Learning is compatible with a wide range of platforms and programming languages, facilitating integration with various systems and technologies. Firebase Predictions is primarily designed for mobile and web applications, offering optimized prediction capabilities for these specific platforms.

6. Pricing Structure: Amazon Machine Learning follows a pay-as-you-go pricing model, charging users based on the amount of data processed and the resources utilized. Firebase Predictions, on the other hand, includes predictive analytics as part of the Firebase platform, with pricing based on overall usage of Firebase services and resources, offering a more bundled approach to cost management.

In Summary, the key differences between Amazon Machine Learning and Firebase Predictions lie in their ecosystem integration, training approaches, scalability options, customization capabilities, supported platforms, and pricing structures.