[skybrian]

In astronomy, aren't they in some sense equivalent? Andromeda galaxy is 2.5 million light years way, so we are seeing it as it was 2.5 million years in the past.

[unethical_ban]

No. Light year is the distance.

Distance/time * time = distance

Waiting a "light year" would be a year.

Yes, you are correct that astronomers talk about seeing into the past by X number of years when we look at a galaxy X light years away.