Final answer:
The rhyme scheme is the third component of a poem's metrical pattern, exemplified by patterns like a,b,a,b. Meter describes the rhythmical pattern, such as iambic or trochaic, defined by stressed and unstressed syllables within a line of poetry.
Step-by-step explanation:
The rhyme scheme is the third building block of a poem's metrical pattern and may be expressed as a,b, a,b, among many other patterns. A rhyme scheme is the pattern of rhymes at the end of each line of a poem or song. It's usually referred to by using letters to indicate which lines rhyme; for example, the rhyme scheme a,b, a, and b means that the first and third lines rhyme with each other, and the second and fourth lines rhyme with each other.
The rhythmical pattern of a poem is called its meter, which involves the arrangement of syllables into repeated patterns called feet within a line. Different popular meters in English poetry include iambic, trochaic, anapestic, and dactylic, each with its own specific pattern of stressed (/) and unstressed (x) syllables. For example, an iambic pentameter is a line of poetry with five feet, each foot being an iamb - a pair of syllables where the second is stressed and the first is unstressed (x/).