I've seen a few ways of discussing the age of a person.
As well as:
college aged students
college age students
When should I use "age" and when should I use "aged"? What is the difference between the two?
Aged means that the person or people you are referring to is/are of the given age. It's always referring to someone. In this case what follows the verb to be is an adjectival phrase acting as a complement, and since it is talking about the subject, it's specifically called a subjective complement. But the important thing is that the main form of [aged 12] is that of an adjectival phrase.
Aged can usually be replaced with of age:
Now, when talking about age alone, age is a noun and [age 11] is a noun phrase. In the case of your examples, [college aged students] and [college age students] represent two different cases of noun modification.
[College aged] is clearly an adjectival phrase.
In the first case, [[college aged] students] you are modifying a noun [students] with an adjective, which is correct.
In the second case, [[college age] students] you are modifying a noun [students] with another noun, which is also correct.
Summing up: for the specific case of the question, it would be the same and would have almost the same exact effect to use either [college age students] or [college aged students].
Per the Macmillan dictionary, aged is an adjective:
In the second case, a group of students that are of college age are college age (not college aged) students. Note the preponderance of college age over college aged in the literature:
First off, you can get around this problem by writing: "He is 20 years old." Eduardo, I have never seen: "He is of age 20." It sounds like crap, and "he is aged 20" sounds horrendous, as well. You should keep in mind that what sounds good or bad is based upon usage and not upon grammar, which is difficult for a non-native English speaker.
Anyhow, the only time I would ever suggest using the word "age" to describe someone's age is in the following example:
"Thomas, age 21, brown hair and blue eyes, was found dead on the railroad tracks near Papa Joe's Bar." Note the use of commas. I could hear the expression being used in true crime novels to describe a victim. Here, "age" is being used as a noun in the same way that his brown hair and blue eyes are. The fact that the description is so clipped, so fragmented gives one the impression that this description comes from a police report. I would avoid this expression at all costs and simply use "20 years old." It sounds more natural, and I bet that you don't want to write a true crime novel.
You could use the expression "at the age of 20", but an action verb is typically expected: ex. "At the age of 20, he won the lottery."
I agree with the second poster that in the sentences he posted, "aged" is being used as an adjective, notably in the second example, "Men aged between...," notably because the adjective comes after the noun as would a past participle, cf.: "The men seen by the woman..."
"A woman aged 50" sounds like crap -> "A 50 year old woman"
I do agree with Eduardo that "college-aged" is better when it's being employed as an adjective: ex. "college-aged students". I recently noticed a similar error in an article from the Daily Beast, which was discussing "small-size businesses [sic]" -> "small-sized [with a "d" because it's an adjective] businesses" (i.e. do not base your grammatical knowledge on the Daily Beast).
Back to the second poster...your graph doesn't prove jack shit. In fact, most Americans would say, "If I was 21 years old, I would be able to get trashed in a bar," whereas normally the conditional should be used: "If I were 21 years old," i.e. the majority is not always right, darlin'.
Hopefully, the original poster sees that there is no cut-and-dry rule. You have to have a feeling and then verify it with your knowledge of grammar. Most Americans have no conception of what a past participle or a gerund is (since grammar is rarely taught in our school system), so we are typically of little help when it comes to grammar, going on intuition rather than on grammatical rigor (mixed with an ounce of intuition, as well).
As a side-note, I find that Time magazine is well-written; there are rarely all that many errors in any given article.
I just reread Eduardo's answer, and I have to say that his comment that "college age students" is fine because "college age" is being used as a noun is entirely wrong. "College age" can never stand on its own, and therefore the adjective, "college-aged," is to be preferred. I challenge you, Eduardo, to come up with a single sentence using "college age" that doesn't sound like donkey doodoo. :-)
Quick comment: you can also write "He is 20," instead of "He is 20 years old" (but never "He is 20 years").