The words ‘ballad’ and ‘ballade’ are often used interchangeably primarily because speakers, including native English speakers and teachers of the English language, assume they mean the same – a narrative poem. The fact, nonetheless, is different. If you look up these words in a good dictionary, you will get distinct meanings, thus conveying that they are not just different from each other but poetically unique in their own way. It is worth mentioning that while ballads can fall under the free verse or fixed verse form of poetry, ballades solely belong to the fixed verse form. Furthermore, the latter has stricter rules than the former.
English sonnets generally possess an element of love or romance, but as has already been stated, modern sonnets can deal with social issues, politics, nature, and even death of a loved one. Be that as it may, English sonnets are phrased in iambic pentameter, which is a line of verse with five metrical feet, each consisting of one short (or unstressed) syllable followed by one long (or stressed) syllable. The sing-song effect generated by English sonnets is by reason of this very meter.
Villanelles are not easy to compose; for while on the one hand, they have strict rules pertaining to the repetition of verses, on the other hand, they are required to follow a rhyme scheme. There are only two repeating rhymes throughout, which means that each of the tercets uses the rhyme scheme ABA while the quatrain uses the rhyme scheme ABAA.