People not entirely familiar with the genre tend to aggregate, in their minds, all chant music of the Roman Rite as one type of "Gregorian Chant," all of which are alike in the same way that various forms of Vivaldi violin concerti are roughly the same stylistically. This is far from being the case. To speak of Gregorian Chant is like speaking of the symphony, which can include Mozart or Mahler. There is a vast variety of chant, each chant carefully crafted to achieve its liturgical and ritual purpose.
An excellent example occurs on Easter morning in the remarkable contrast between two pieces the precede the Gospel reading. The Alleluia chant Pascha Nostrum is one of the most elaborate I've seen the books, a full three lines of notes that cover only five words: Pascha nostrum immolatus est Chistus, that is, Christ, our paschal lamb, has been sacrificed. It is a chant to be sung by specialists and elicits high level contemplation on the great mystery of what has happened during the Triduum: from death to life to salvation.
Here is the image and here is an audio file.
In marked contrast, have a look at the Sequence, which precedes or follow the Pascha, depending on the use (the ordinary form in the US permits the Alleluia to follow the Sequence, but this is not normative or traditional).
Note that we have one note per syllable here. It is poetry, not prose. It has a striking and memorable melody you can take home with you. To sing them back to back permits us to see just how great the variety is within this thing we called Gregorian music.
Here is the chant and here is an audio.