About Rheo units
Rheo is the AI assistant built into Splice Create, and Rheo units enable it to keep working. Every action, suggestion, or reply that Rheo gives you during a conversation uses Rheo units, including (but not limited to):
applying effects and automation to tracks
showing you production tips in Pointer mode
renaming or grouping tracks
searching the Splice catalog for loops & samples
Rheo units are not used to download and license samples from the Splice catalog-- they're used to power conversations with, and actions taken by, Create's AI assistant Rheo.
About Splice credits
Splice credits are used to purchase and download samples, presets and packs on Splice. If you're on a Splice Creator or Creator+ plan, they're also used to license Splice samples when exporting a project in Create.