Strophic form (also called chorus form) is a sectional/additive music structure based on the repetition of one musical block, like A A A... or A A' A".... Like poetry where the rhyme scheme repeats in each stanza, the musical block of strophic form repeats the same music with no variations or minor variations. Most popular and folk music is written in some kind of strophic form.
The thirty-two-bar form A A B A is common in Tin Pan Alley songs and some later rock, pop, and jazz. The thirty-two-bar form focuses on the verse (A), which typically contains the main melody and contrasts with the refrain/bridge (B). It's called the thrity-two-bar form because each chorus is comprised of four eight-bar sections. The thirty-two-bar form was often used in 1950's and 60's rock. "Somewhere Over The Rainbow" is an example of a thirty-two-bar song.
Unlike the verse-focused thirty-two-bar form, the verse-chorus form highlights the chorus. The chorus often sharply contrasts the verse melodically, rhythmically, and harmonically, and assumes a higher level of dynamics and activity. The verse-chorus form is common in post-1960's rock.