1. Integration Capabilities: Amazon API Gateway is designed for creating, publishing, maintaining, monitoring, and securing APIs at any scale. On the other hand, Smartling is a translation management solution that helps companies translate digital content. While Amazon API Gateway focuses on API management, Smartling specializes in content translation and localization.

2. Target Audience: Amazon API Gateway is suitable for developers and organizations looking to create and manage APIs for their applications. On the contrary, Smartling is more applicable to businesses that need to translate and localize their digital content to cater to a global audience. The target audience for each tool differs as they serve distinct purposes in the tech industry.

3. Supported Languages: Amazon API Gateway primarily supports API development using programming languages like Python, Java, and Node.js, among others. In contrast, Smartling supports translation for various languages, enabling businesses to localize their content for numerous regions. The range of languages supported is a significant differentiator between these two tools.

4. Functionality: Amazon API Gateway provides features related to API creation, management, and monitoring, offering a comprehensive solution for API development. Conversely, Smartling focuses on translation services, offering functionalities that aid in the localization of digital content. The core functionality of each tool is tailored to their specific roles in the software development and localization processes.

5. Cost Structure: Amazon API Gateway follows a pricing model based on API calls, data transfer, and caching, which may vary depending on usage levels. In contrast, Smartling's pricing is typically determined based on the volume of content to be translated and the level of support required. The cost structure of these tools differs, catering to the distinct needs and usage patterns of their respective users.

6. Security Focus: Amazon API Gateway incorporates security features such as authentication, authorization, and encryption to ensure the protection of APIs and data. Conversely, Smartling emphasizes data security and compliance in the translation and localization process, offering features like secure data transfer and storage. The focus on security differs between these tools, aligning with their specific functionalities and user requirements.

In Summary, Amazon API Gateway is primarily focused on API management for developers, while Smartling is geared towards translation and localization services for businesses. Their differences lie in integration capabilities, target audience, supported languages, functionality, cost structure, and security focus.