While the OP specifies the US, some of the other answers are based on other countries.
I'll answer I'll respond mainly to thatregarding the US, but first forI'll start with some comments regarding other countries.
In In many countries college, college means secondary school, afterfollowing on from primary school. It would never mean that to the average American.
Technically (in the US), a US college is a venue for obtaining post-high school (post-secondary) qualifications. It could be a 2-year degree, called an Associates degree, which may or may not be vocationally-based. You can get an AA or AS in welding or in, math or in, Spanish or.., etc.
Those These colleges are usually called Community Collegesknown as community colleges.
The other type of college grants Bachelor's degrees (not to be confused with the bachillerato granted in many countries to what in the US would be called high school students, who are typically headedgoing on to what in the US would be called college).
There There are 4-year liberal arts colleges, and there are subject-oriented colleges (rarewhich are now rare).
In the US, a Universityuniversity would be composed of multiple colleges, including theone or more bachelors college (or several)colleges, as well as a grad school. You really shouldhave to offer a Masters degree to be able to call it a Universityuniversity.
Most
Most Universities also offer PHPh.D.s and maybepossibly other advanced degrees (in the American academic world, we now call the MA and beyond terminal degreesterminal degrees), such as MD, JD, THD, etc.
Some
Some places, like Boston College, have chosen to keep theCollege in their name College, even though it is a universitythey are universities.
No, I would not say I'm"I'm going to University,university"; I'd say I'm"I'm in collegecollege" (though for my last degree I was actually taking classes in three colleges of the Universityuniversity).
I could say that I'm"I'm at the University of CaliforniaCalifornia", or I"I go theto Yale UniversityUniversity", but not I'm"I'm in universityuniversity" (or Uni"I'm in Uni"), without it sounding a bit affected.
So if all I said was that my daughter was off to college, you wouldn't know if she was inattending a small liberal arts school of 300 or attending a prestigious university, or even a local community college (but then why say she was "off to?") -- but you would know that she was studying at a level beyond the high school level.
People who are not in academicsacademia might say somethinguse the term without knowing all these details.