Epic	Romance
heroic age	chivalric age
weight, solidity	mystery, fantasy
tragic, serious	light-hearted
narrative unity	loose structure
love is absent	love is supreme
characters speak for themselves	narrative voice
oral	literate
didactic	subversive
Yvain enters the battle between the dragon and the lion. -- Chretien de Troyes

From a Handbook of Literature (a general, vague definition)
A tale of adventure in which knights, kings, or distressed ladies, motivated by love, religious faith, or the mere desire for adventure, are the chief figures. The medieval romance appears in Old French literature of the twelfth century […]. The epic reflects an heroic age, whereas the romance reflects a chivalric; the epic has weight and solidity, whereas the romance exhibits mystery and fantasy; the tragic seriousness or the epic is not matched in the lighter-hearted romance; the epic observes narrative unity, whereas the structure of the romance is loose; love, usually absent or of minor interest in the epic, is supreme in the romance; the epic uses dramatic method of having the characters speak for themselves, whereas the reader of the a romance remains conscious of a narrator. (Harmon)

Some Observations (Notice the contradictions.)

Audience
The audience for these early vernacular narratives was largely made up of women--the queen, duchess or countess and the other ladies of her court. These women naturally tended to be interested in stories in which women played more central roles than was true in Germanic epics such as Beowulf (which centered almost exclusively on the exploits of male warriors). Because the vernacular language poet's livelihood depended upon pleasing his/her audience, the vernacular narratives written for these courts ("romances") tended to focus on other plot developments than the fighting and male-bonding emphasized in epic poetry. The narratives still concern the deeds of brave warriors, but the Middle English knight (unlike the Old English thane) is motivated by love for his lady. Accordingly, women play an increasingly important and active role. –Deborah B. Schwartz

Adultery and Subversion
But the substitution of one form of control for another rent the fabric of feudal society. A courtly lover, bound to his lord by ties of homage and duty, found himself bound to an even further degree to the lord's lady. Feudal loyalty was split into different and sometimes opposing obligations.

Courtly love, whose beginnings lay in the social control of the culturally disruptive sexual urge, became an immensely powerful movement under the leadership of Eleanor of Aquitaine. As Patricia Terry says, "... courtly poets raised love to the same important level as religion and warfare within the realm of poetry. Ecclesiastical poets had celebrated the fidelity of saints and martyrs. [...]!" (x-xi) The idea saturated Provençal culture, but failed, ultimately; to do the very thing it first set out to do reduce the friction and dissension that love caused to the feudal system. Courtly love defied the social order by making love more important than politics or religion.--Robert V. Graybill

The Role of Romance
Perhaps surprisingly, any "love interest" is likely to be incidental to the story of a medieval romance. An exception to this rule may be found in the breton lai: the term refers both to the relatively brief form of medieval French romances, professed to have been sung by Breton minstrels on Celtic themes, and to the English medieval poems written in imitation of such works. These romances often wove their stories around a famous legendary figure (Arthur, for example, or Tristram) and took as their immediate subject matter a love story of some kind. –Jonathan A. Glenn

Characteristics of the Medieval Romance
A tale of High Adventure. Can be a religious crusade, a conquest for the knight's leige lord, or the rescue of a captive lady or any combination.
Characterized by:
1. Medieval romance usually idealizes chivalry
2. Medieval romance Idealizes the hero-knight and his noble deeds
3. An important element of the medieval romance is the knight's love for his lady.
4. The settings of medieval romance tend to be imaginary and vague.
5. Medieval romance derives mystery and suspense from supernatural elements.
6. Medieval romance uses concealed or disguised identity.
7. Repetition of the mystical number "3." (Repetitions of the number or multiples of 3)
-- http://www.loyno.edu/~MidAges/