Definition of standard terminologies that are used to describe Microsoft software updates :

• Critical Update
• Definition Update
• Non-Security Update
• Security Tool
• Security Update
• Service Pack
• Update Rollout

Patch Management 8.x, ITMS 8.x

1. Critical Update : A vulnerability whose exploitation could allow code execution without user interaction. These scenarios include self-propagating malware (e.g. network worms), or unavoidable common use scenarios where code execution occurs without warnings or prompts. This could mean browsing to a web page or opening email. Microsoft recommends that customers apply Critical updates immediately.
2. Definition Update : Definition update is a Windows update that adds or modifies the definition database of Windows operating system; A definition database is a database that is built into the operating system to help it identify malicious code, phishing sites, and junk mail
3. Non-Security Update : A fix for a specific non-critical, non-security-related problem.
4. Security Tool : A utility or feature for completing a task or set of tasks.
5. Security Update : Updates that address security-related issues in an operating system are called security updates; These Windows Updates are generally issued after some security organization finds a fault in any operating system and notifies Microsoft; Microsoft creates a patch (update), asap or within a fixed period, to fix those issues; The update is then released worldwide; often users are also notified via email to download these security updates
6. Service Pack :  It is a cumulative set of all hot fixes, security updates, critical updates, fixes, and updates. It is a set of Windows Updates that were released between two successive versions of Windows operating system. The age of Service Packs is over now.
7. Update Rollout : A cumulative set of hot fixes, security updates, critical updates, and updates that are packaged together for easy deployment.