Castle vs deppbot: What are the differences?

Castle: Track security events or any unstructured data from your web backend or mobile app, and Castle will look for anomalies. Castle looks for suspicious login patterns without bothering the legitimate user nor the site administrator. The fully-automated anti-hijack engine identifies potential account compromises based on where the user logs in from and how they navigate the site; deppbot: Automated Security and Dependency Updates for your Ruby apps. Based on your configured schedule, deppbot will run bundle update on your Ruby app and send the result as a Pull Request to GitHub. deppbot will also check your app periodically for any RubyGem vulnerabilities and fix it automagically.

Castle and deppbot belong to "Security" category of the tech stack.