Other platforms successfully use colorisation to distinguish local / global entities within a document. We might explore doing the same for template parts and reusable blocks.

There's some backscroll in issue #26599 for context. That issue was closed as it touched on many other related (and now resolved) template-part-related concepts.

Colorisation considerations

• List view (resting, hover, and active states)
• Canvas (outlines / overlays in select mode and the Site Editor, Block Toolbar)
• Inspector (icon in the Block description)
• Inserter (block icon)

Purple could be a good option, but might clash a bit with the "Ectoplasm" color scheme. Speaking of which, this color(s) should probably be static and not change with the specified color scheme.

I've seen green suggested for Reusable Blocks in other issues.

Figma file here to explore :)