Currently, in the U.S. consumers of gasoline pay a per-gallon tax rate for each gallon of gas purchased. As shown in the text, this tax reduces supply, which results in increased prices and decreased quantity. 

As an alternative, some people have suggested a replacement for the gasoline tax. Instead a vehicular user fee would be charged for each mile driven.

Is there any economic distinction between a “tax” and a “fee”? Explain.