The most distinguishing differences between the epic poem El Cantar de Mio Cid (or The Lay of the Cid ) and classic Greek epics are the date of composition, identity of the heroes and the versification. It is generally agreed by scholars that Mio Cid was taken down as a dictation from an orally performed poem. The oral poem has been dated by Ramón Menéndez Pidal as circa 1140 A.D. with an anonymous authorship. Greek epics, on the other hand, such as the most famous two, Iliad and Odyssey, are dated from much earlier circa 800 to 600 B.C.
It is well known that El Cid, the hero of Mio Cid was a real historical person and that he was exiled, did have mighty adventures and was recalled to the court of King Alfonso--who trembled from a crushing military defeat--from whose court El Cid (El Cid is the equivalent of English Sir) was exiled. On the other hand, Greek epic tales, which are filled with gods and demigods, are based on heroes from such dim recesses of time that they are generally considered to be mythical figures, although Robin Lane Fox in Pagans and Christians contests this point.
The versification techniques of Mio Cid in the original language of Medieval Spanish has the element of final-word assonance, which means that while rhyme isn't used, the vowels of the last words have assonance, or a matching sound, as in the second laisses ending with the words: riendas; diestra, siniestra, cabenza, destierran, and Castiella. The stanzaic structure is that of the laisses, a structured that appears to have been borrowed from French epics. The Medieval Spanish epic form is not a metered form. Instead of meter, each line has a strong hemistich, which is Medieval English epics is called the caesura, that is a pause in the midst of a line, which is preceded by four syllables and followed by six syllables ( / / / / -- / / / / / / ).
In Mio Cid, there are 152 laisses, each with assonance. One of the most striking features is the irregularity of the lines with some long and come very short, such as "y aún además los ojos de las caras. / ... / mas el Criador os guarde con todas sus virtudes santas." Although, P. T. Harvey and A. D. Deyermond theorize that if sung, then the lines of Mio Cid become regular due to the rhythmic requirements of song.
On the other hand, versification features of Greek epics are based on the linguistic principle of duration--a feature that English does not possess--wherein some vowels are held for more beats than other vowels; in other words, some are held for a longer length of time than others. Greek epics do not use rhyme but does use alliteration (the repetition of beginning consonant sounds, e.g., Bert's bouncing bunny boinged) and assonance (repetition of vowel sounds), although the assonance is not final-word specific as in Medieval Spanish epic versification.
Greek epics are a metered form of poetry. The epic meter is dactylic hexameter with a pattern of / ^ ^ for six meters: / ^ ^ / ^ ^ / ^ ^ / ^ ^ / ^ ^ / ^ ^ . Unlike English, the rhythmic pattern isn't tied to syllabic stress (e.g., ap/ ri^ cot^) but rather to vowel duration as defined above--a linguistic feature not present in English--therefore the dactylic pattern in the Greek epic is a long vowel syllable followed by two short vowel syllables, which have duration, or length in time.