Compare and contrast `tags` versus `metadata` usage

### Contributions

- [X] I have read the contribution docs, and understand what's expected of me.

### Link to the page on docs.getdbt.com requiring updates

https://docs.getdbt.com/reference/resource-configs/meta#designate-a-source-column-as-containing-pii

### What part(s) of the page would you like to see updated?

I would like to see compare and contrast information on using tags versus metadata to denote things like PII. What is the functionality difference? Is there anything different besides being able to use it in a dbt `--select` or `--selector`?

### Additional information

It would be helpful to me to see a screenshot of how metadata displays in the dbt docs site generated.