It seems deliberately confusing to me since there is no fundamental difference between voting now and voting on the day of the deadline, but the way it’s discussed and referred to seems to imply that the correct day to vote would be waiting until the last minute instead of voting just getting it out of the way weeks ahead of time.
Once upon a time we had Election Day. The polls were open for one day. Election Day, Nov 5, is still a thing, in the modern era they can tabulate votes fast enough to call the election that night. The practice of opening the polls before Nov 5 is called early voting. It’s basically that simple.
In my state, the local polling stations only open on Election Day, to vote early you have to go to a government building up at the county seat where they have one voting center open, so there is a practical difference.