An earth year is a unit of time.

A light year is a measure of distance.

A light year is the distance light will travel in a vacuum over the period of one (earth) year.

Since light travels at about ##186,300## miles per second, with ##86,400## seconds per day and about ##365## days per year, that works out at about:

##186300xx86400xx365 ~~ 5,875,000,000,000## miles.