https://www.cnet.com/how-to/mail-in-...he-difference/
They are.
Every US state allows mail-in, absentee voting, but typically only under certain circumstances. For example, in the past, many states only allowed you to get an absentee ballot if you were deployed with the US armed forces, were going to be out of town on Election Day or were ill.
Amid the pandemic, however, at least 35 states have changed their mail-in absentee voting policies, allowing all voters to apply for an absentee ballot to cut down on the risk of spreading the virus. Some states are calling the expanded criteria for absentee voting "no-excuse absentee voting," a term that indicates you don't need to explain why you want an absentee ballot as you have in the past -- but you'll still need to fill out an application and request one, either online or through mail.