I think the difference is that with mail in ballots, they are concerned that ballots will be sent out wholesale, to every registered voter, so my dead mom would get her ballot, even though she died four years ago. That would allow someone to vote on her behalf. Someone could conceivably pretend to be an official that went to previous homes of the departed, and gather their ballots. Then they could vote in behalf of the dead.
Absentee, you actually have to request the ballot. If it is done like Arizona, as long as you keep voting, you keep getting the ballot. There is still a potential for fraud, but no more than going into a polling place with nothing more than a name to vote.
If you don't make someone elses life better, what good is yours?
Weighty decisions are easy to make, when you aren't burdened by all the necessary information
The inherent vice of capitalism is the unequal sharing of blessings. The inherent virtue of communism is the sharing of misery. -Winston Churchill
If you think the United States is bad, think of another country that wants to put troops on the border to keep illegal aliens out, instead of walling in their citizenry