Three dimensions, compared directly

Extension type, distribution or scope, and execution side
Extension typeDistribution or scopeExecution sideRuntime model boundary
Ordinary pluginProject or machine-local source in this comparisonClient/orb sideSeparate ordinary plugin child process
Global pluginPersonal or workspace; available beyond one project or machineClient/orb sideOrdinary plugin runtime model; distribution differs
Declarative server-only agent/toolSeparate declaration system, not a plugin scopeServer sideDo not inherit the ordinary child-process diagram
Safe inference

Ask each question separately.

First identify the extension type. Then ask how broadly it is distributed. Finally ask where it executes.

Boundary

This is not a product taxonomy.

The comparison protects the article's runtime model. It does not catalogue every Amp extension or internal server behavior.

The official Global Plugins and Skills guide defines global in terms of availability and scope. The official Plugin API reference documents declarative server-only agents and server-side tool execution. This scene keeps those dimensions separate.