Throughout my studies in music I've found the question that you ask to be one of the more difficult to answer. Instead of a person speaking and trying to explain verbally what the concept of musical modality is...it is often easier to hear it musically. I'll give you an example of how modes are applied in real life.

Most southern rock is played in a pentatonic manner. The mode translates closest to Aolean...the name of the mode is irrelevant. What is important is the sound and feel of this particular mode. It feels bluesy and loose. Skynard, 38 Special, etc...

When you hear Joe Satriani or Steve Vai, more often than not, your hearing a Lydian modality. Lydian is semi-happy, semi-sad, melancholy and smooth.

Most Egyptian and Chinese music stem from the Phrygian mode (although not directly). This particular mode is common in Egyptian music. It give an odd and dark kind of vibe. It has a high level of tension and release when phrased properly.

Again, this is just my insight. The truth is out there, young axeslinger...follow your ears!