simply did not exist in medieval Europe. For instance, West African polyrhythmic beats and Latin American syncopation are common elements in much of today's music, regardless of its origin. Even music with a very regional identity will still contain influences from other places and peoples. Therefore, if you listen to music today of just about anygenre, you can detect influences from around the world. Conversely, medieval Europe was an insular world with few outside contacts. Therefore its music was much more homegrown with less variety.

Language is also something to consider. Most music of medieval Europe was liturgical and therefore sung in Latin. As such, the lyrics were not understood by most of the populace. Music today is usually composed in the vernacular and in languages understood by most of its listeners. However, medieval minstrels often sang songs and ballads in everyday languages. These minstrels sang as a form of popular entertainment and served a purpose similar to today's musicians.

Today, most music is a blend of instrumentals and vocals. Medieval music on the other hand seldom utilized instruments. Therefore it lacked much in the way of rhythm, although chanting could be either polyphonic or monophonic, meaning it contained several or just one melody.

One issue here is whether you are using "modern" in a scholarly sense, referring to the period after the Renaissance, or in a popular sense, to mean contemporary, or, in a narrower way, to refer to "modernism," a specific movement of the first half of the twentieth century.

On a very general level, the technologies of sound production and reproduction have changed. For example, the flute was originally a wooden instrument and only evolved into its modern metal form in the nineteenth century. Instruments such as the clavichord, dulcimer, and harpsichord existed in the medieval period, but the piano was a seventeenth century invention, designed to allow greater variation in volume and expressiveness. Electric and electronic instruments, such as the electric bass and guitar, synthesizer, and drum machine were twentieth century inventions.

Another major technological difference is the invention of mechanical reproduction of music. While in the medieval period, one encountered music solely in live performance, but starting in the late nineteenth century, it became possible to hear recorded music.

Finally, although secular music certainly was common in the medieval period, religious compositions and venues were proportionately more important than in the twentieth century, with churches providing important venues for performance and religious themes dominating many of the more important works of the period.

Medieval music and modern music have more in common than you might think. Just like today, medieval music was split between religious tunes and secular (i.e., non-religious) tunes. Today, however, both the religious and secular music genres have many, many sub-genres. In secular music, for example, there are sub-genres, such as rock, rap, country, and jazz, just to name a few. Those sub-genres have sub-genres, too, like acid jazz, smooth jazz, hard bop, ragtime—the list of jazz sub-genres alone could easily fill a sheet of paper. In medieval times, secular music was broken down into two sub-genres: ballads and folk songs.

Medieval songs were often about one of two topics: love, which remains arguably the most common song subject in the modern era, or bravery in battle, which has not remained popular. Medieval musicians strummed, beat, or plucked many of the same instruments that your favorite bands do today, too, such as drums, horns, and lutes, the last of which occupied much the same place that guitars do today. Medieval artists also played several instruments, such as the zither, zink, and hurdy-gurdy, which are very rarely featured in modern music, if they're used at all. Religious songs were sung or chanted without accompaniment.

Finally, secular musicians in the medieval era were often troubadours, which means they wandered from locale to locale with their lute or other accompanying instrument, singing songs and sharing news. Today, music buffs shell out big bucks to descend upon a club or arena for a concert; in medieval times, the concert came to you, often whether you wanted it to or not.

These terms – medieval music and modern music – need a little clarification and subdivision.  Secular medieval music forms (ballads, love songs, etc.) are best compared to modern music (Top 40?  UTunes?) in that they have similar traits – wide popular appeal, current instrumentation, thematic subjects of personal emotions (love, loneliness, forlornness, etc.).  Religious medieval music (western) featured choral work and subjects related to the liturgy, mass, etc., and were composed to be performed in churches and cathedrals.  Modern “classical” western orchestral music, far from popular appeal, is now pretty much confined to elitist, sophisticate audiences in concert halls.  (The term “modern” here includes 19th century composers such as Ravel, Faure, Mendelsohn, etc., but really should be confined to Arvo Part, Philip Glass, and the like).  The more glaring difference between the two periods might be the technology, not only electification of instruments and airwave for distribution, but most importantly, the ability to record and replay music, while in Medieval times the music was written down in notes and replayed at each performance.  The forces, too, of the Free Enterprise System vs. medieval systems of patronage have changed the forms of music’s distribution (large concerts vs. private reception halls.)