How different is “different”?
Some people so very badly want space aliens to be real!
A “top scientist” at NASA has suggested that “tiny super-intelligent” ETs may have already visited earth and that we need to rethink our whole concept of aliens (https://www.thesun.co.uk/tech/7885699/nasa-aliens-alien-life-ufo-sightings/).
See, they might be so profoundly different from what we expect, we wouldn’t even realize they were intelligent life. It depends on what “is” is. Like, for aliens that resemble, say, handfuls of sand and have a life-span of millions of years, interstellar travel would be no big deal. Anyway, the “top scientist” says we ought to step up our search for intelligent extraterrestrial life. He does not say why.
To look at it from another angle, we might be so totally different from them, that they wouldn’t even recognize us as being living things, let alone intelligent life.
This could lead to some really cool science fiction stories and movies–if there were still some really cool science fiction writers around to write them. C.L. Moore, James Blish, Theodore Sturgeon–ah, what you could’ve done with this material!