1. Key Difference 1: Data Discovery and Classification IBM Guardium provides robust data discovery and classification capabilities which can automatically locate sensitive data within the organization's databases, file systems, and cloud environments. It uses machine learning techniques to identify and categorize sensitive data based on predefined rules, metadata analysis, and pattern recognition. In contrast, Imperva lacks advanced data discovery capabilities and primarily relies on manually defining data classifications, making it less efficient and more prone to human errors.

2. Key Difference 2: User and Entity Behavior Analytics (UEBA) IBM Guardium includes built-in user and entity behavior analytics (UEBA) functionality, which can detect abnormal activities and suspicious behavior patterns of users accessing sensitive data. It uses AI and machine learning algorithms to establish baselines of normal user behavior and identify potential insider threats or unauthorized access attempts. Imperva, on the other hand, does not offer native UEBA capabilities and requires integration with third-party solutions to achieve similar functionality.

3. Key Difference 3: Real-time Monitoring and Alerting IBM Guardium excels in providing real-time monitoring and alerting capabilities to detect and respond to potential data breaches or policy violations promptly. It continuously monitors database activities, network traffic, and file system access to identify any suspicious or unauthorized activities. It can generate real-time alerts and notifications to security personnel, ensuring immediate action can be taken. Imperva offers similar monitoring and alerting capabilities but may not be as comprehensive or as real-time as Guardium.

4. Key Difference 4: Database Vulnerability Assessment IBM Guardium includes functionalities for assessing and identifying potential vulnerabilities in databases. It can scan databases for security weaknesses, misconfigurations, and outdated software versions, allowing organizations to proactively address these issues before they are exploited by attackers. Imperva does not offer built-in vulnerability assessment capabilities and requires separate tools or manual processes to perform similar assessments.

5. Key Difference 5: Transparent Data Encryption IBM Guardium provides transparent data encryption capabilities, allowing organizations to encrypt and protect sensitive data at rest within databases and file systems. It ensures that even if the data is accessed or compromised, it remains unreadable and unusable without proper decryption. Imperva offers limited encryption capabilities, primarily focused on securing data in transit rather than at rest.

6. Key Difference 6: Compliance and Audit Reporting IBM Guardium offers comprehensive compliance and audit reporting functionalities, facilitating organizations' adherence to regulatory requirements and industry standards. It provides pre-built templates and customizable reports, enabling efficient monitoring and reporting of security controls, data access, and data protection measures. Imperva also provides compliance and audit reporting capabilities, but its reporting features may not be as extensive or customizable as Guardium's.

In Summary, IBM Guardium stands out from Imperva with its powerful data discovery and classification, user and entity behavior analytics (UEBA), real-time monitoring and alerting, comprehensive database vulnerability assessment, transparent data encryption, and compliance and audit reporting capabilities.