Tax rate vs. effective tax rate
The municipal tax rate is applied to assessed value; an effective tax rate expresses tax relative to estimated true market value, making cross-town comparisons more meaningful.
New Jersey example
Two towns can show very different nominal rates simply because their assessment levels differ.
Official source
https://www.nj.gov/treasury/taxation/lpt/localtax.shtml
This is a plain-English summary. Rules and dollar amounts change, so check the official source or a professional before you file or sign anything.