Asking to differentiate between these musical genres is like asking someone to describe the difference between a computer and a phone. Once upon a time, there was a clear delineation.
In
general - bearing in mind that these are broad brush-strokes, a hymn is:
- Metrical - fitting into a standard English syllable pattern and rhyme scheme
- Strophic - divided into verses of equal length and identical meter
- Homophonic - all the voice parts move together in more or less the same rhythm
- Participatory - intended to be sung by the entire assembly
- Accessible - singable by musicians and non-musicians alike in terms of range and harmonic/rhythmic complexity; this usually means
- A melodic range of a tenth (octave + 3rd) or less
- All voice parts within standard ranges for those groups (sopranos below E5, altos below C5, tenors above C3, basses above E2)
- Rhythms comprised primarily of half, quarter, and eighth notes
- Primarily diatonic harmonies with occasional forays to the dominant, relative, or parallel keys (this means that in C major, you might go to G major, A minor, or C minor somewhere in the middle of the verse - but you might not!)
- Traditionally orchestrated - generally intended for a congregation or choir, either a cappella or with "classical" polyphonic instrumentation: piano, organ, or orchestral instruments - and usually capable of being rendered equally well either with or without instruments
Hymns as a genre are NOT defined by complexity of lyrics or music, especially with the advent of American hymnody. Lutheran chorales are much more likely to be in a minor key and to have a complex non-standard meter, with more involved counterpoint and a wider harmonic vocabulary. English hymns are often more straightforward metrically, with simpler counterpoint, but the depth of the lyrics and the "interest" level of the harmony is frequently comparable to the Lutheran counterpart. It's in American revivalism where you are more likely to find simple lyrics, frequent refrains, and a harmonic vocabulary often composed of 3-5 chords. Incidentally, while it can be easy to look down on those features of American hymnody, one need only find some movie from the 40s, 50s, or 60s that features some of these hymns being sung (say by a group of young men going off to WW2) in order to grasp what a moving experience these hymns could be. They weren't meant to be performed in a German or English church with a pipe organ...
In
general, again bearing in mind that these are broad brush-strokes, a contemporary song may or may not be metrical and strophic; but my rather subjective sense is that one finds a higher proportion of irregular meters and more complex verse layouts (bridge after the 2nd chorus, then back to verse 3, then the refrain two times, etc...). A contemporary worship song will more often be marked by highly syncopated rhythms and is more likely to be "performative", with a wider vocal range and higher difficulty level to the musical line. The harmonies are usually simpler than in most hymns, though the 3-6 chords used may have a more "modern" flavor (meaning that in C major you might have a lot of B-flat major chords instead of G major). Contemporary worship songs are also written with guitars, vocal soloists, and percussion in mind, and they reflect a different approach to music in that instead of having carefully worked-out counterpoint between the four voice parts, you typically just have a bass line and a melody. Yes, many praise songs have 2nd and 3rd counter-melodies, but I believe there is still a demonstrable sense in which the "chord" drives the music rather than the careful correct counterpoint of a proper hymn. Contemporary songs, despite often having less musical substance, are much harder to sing for the average non-musician... there's much less "togetherness". Sadly, because of our society's addiction to novelty and stimulation, the idea of being able to sing together on a metrical psalm or hymn gets written off as "boring". Sigh...
As far as substance goes, while theological depth is not a defining characteristic of a hymn, I do believe there is something unique about the vapid subjectivism and doctrinal barrenness of much modern contemporary music. While American hymnody can be particularly simple, it still at least expresses a basic level of doctrine that is orthodox within the confines of its tradition. That tradition might be Baptist or Wesleyan but regardless, the hymn will give basic and faithful expression to key tenets of its doctrinal home. Not so for a lot of contemporary music which often has completely meaningless or worse, irreverent and banal lyrics. Sloppy wet kiss, anyone? That aspect of contemporary music really does differentiate it from hymnody, though again, I am painting in broad strokes and this does not apply across the board.
That said, with the development of contemporary music as a genre, and its effectively complete takeover of large parts of the American church, the lines have become blurred. I really challenge anyone to show me how, based on the above criteria, "In Christ Alone" or "How Deep The Father's Love" are NOT hymns. Okay, they were written with the traditional CCM ethos in mind, but on every other one of those points, they're hymns. Likewise, when you go to a church and you have the traditional guitar and vocals supplemented by a cello and a baby grand piano, and they're singing "contempified" versions of "Jesus Shall Reign", or "Amazing Grace" with a refrain between each verse. This is because faithful Christians who long for greater depth are realizing that it can be found in some of the older hymns and psalm settings, and they're reaching out to appropriate that material in the only ethos with which they are familiar - the contemporary ethos.
On the flip side, modern hymnals have more and more contemporary songs. Particularly in mainline denominations, each new hymnal has a greater degree of new and ethnically diverse hymns (not to mention doctrinally pluralistic). While I appreciate the trend in contemporary services toward greater use of hymns and psalms, the latter trend is nothing more than deplorable. If there's anything worse than trying to notate a contemporary or ethnic hymn in the music notation of 18th-century western Europe, it's watching two dozen septagenarians in a sanctuary that seats 300 trying to sing such a hymn with organ accompaniment. But in the Reformed evangelical world, a number of otherwise more traditional churches are incorporating better elements of contemporary music, such as newer musical settings of the Doxology or contemporary hymns by figures such as the Gettys.
