Illegal Alien or Undocumented Immigrant.. Are they really the same thing?

I've seen these two terms frequently being used interchangeably, and it makes me wonder... Are they really talking about the same group of people? I've never really thought of Mexicans as being particularly alien in nature..

alien
adj.
1. Owing political allegiance to another country or government; foreign: alien residents.
2. Belonging to, characteristic of, or constituting another and very different place, society, or person; strange. See Synonyms at foreign.
3. Dissimilar, inconsistent, or opposed, as in nature: emotions alien to her temperament.
n.
1. An unnaturalized foreign resident of a country. Also called noncitizen.
2. A person from another and very different family, people, or place.
3. A person who is not included in a group; an outsider.
4. A creature from outer space: a story about an invasion of aliens.
5. Ecology An organism, especially a plant or animal, that occurs in or is naturalized in a region to which it is not native.

Is this simply the use of various euphemisms to describe individuals that enter our country without proper documentation, or are there really two separate groups being defined?

Could the term "undocumented immigrant" refer to individuals that cross our borders from other countries without official permission, while the term "Illegal alien" refers to beings of an extraterrestrial origin that have entered our planet/country illegally?

Is there a secret alien registration department that we are not aware of ? Could all the confusing terminology being used be an attempt to deceive, inveigle and obfuscate the truth as Fox Mulder believes?

Whatever they are, we've had over 2 million of them enter our country in the last year! I may be wrong, but it sounds More like an invasion to me.. But then again, who doesn't want free housing, medical care, food, and an income that's non-work based? Sign me up Uncle Joe!

You might be on to something here.

a reply to: LLoyd45

until they file and then approved or denied their here illegally, hence the the term illegal alien.
they are required by law to cross at the boarder crossings, no where else. where all the legal processes start.

they cross else where because they know they can be turned away at the boarder right then, if they get across the boarder they can stay and file for asylum and stay for how ever long it takes to process it.

originally posted by: LLoyd45
Whatever they are, we've had over 2 million of them enter our country in the last year! I may be wrong, but it sounds More like an invasion to me.. But then again, who doesn't want free housing, medical care, food, and an income that's non-work based? Sign me up Uncle Joe!

All I know is that if you put a couple thousand in sanctuary cities the mayor's and governors all the sudden want to call a state of emergency and have em shipped out