Want to Understand Agent Filter

What is the best way to understand what fields the agent filter creates and what values are actually stored in the fields?

Example Questions
The agent filter creates an field named "os" and a field named "os_name". What is the difference between these fields?

The agent filter creates a device field. How can I understand the different values that are populated in the device field? The device field gets populated with values of "Other" or "Spider"

I can't directly help, but this has been raised before and there is an GH issue to improve the documentation - Does the useragent filter produce two apparently identical os fields?