What is the difference between conditionally responding to an offer, and outright responding?

There are two ways of responding to an offer through QTAC. You can either respond outright or conditionally. An outright response includes accept, defer or reject. Responding outright guarantees that no further offers will be made for any higher eligible preferences.
Conditional responses mean that you have reserved your place or response in this course, while you wait to be considered for higher preferences. This means that if you are eligible to receive an offer in any higher preference, you can still be offered a place in that course, but if the new course is in the same semester, you would lose the rights to your initial offer.