Iambic pentameter is a type of metric line that is very popular in English. In fact, it is estimated that up to three quarters of all poetry written since Chaucer has been written in iambic pentameter. The pattern is an unstressed syllable followed by a stressed syllable. All major forms of poetry, such as blank verse and the heroic couplet can use iambic pentameter.
The main style difference between “Roses” and "Night" is that A. "Roses" uses iambic pentameter. This means that each line has 10 syllables (1 meter = 2 syllables) and that the first syllable is unstressed, whereas the second one is stressed.