Medieval - Basically pretty simple, music kind of was based around one line melodies - there wasn't really too much rhythm. It was all just Gregorian chants and what is called 'plainsong'. Maybe some wandering musicians playing uncomplicated popular melodies, nothing too complex.
Renaissance - Starts to show more complexity with multiple 'voices' either instrumentally or vocally. Composers were starting to get interested in the richer sound and possibilities of using multi-voiced pieces.
