In the quote from J. Courtney Sullivan's book "Commencement," April is described as having a small, fleeting amount of craziness, comparing her to a Dixie cup. This suggests she experiences moments of instability or eccentricity but on a limited scale. Lydia, on the other hand, is depicted as having a much larger capacity for craziness, likened to a twenty-gallon tank, indicating she is far more intense or unpredictable.

The imagery emphasizes the contrasting personalities or emotional states of the characters, highlighting how Lydia's tendencies are more significant and possibly more overwhelming than April's. Sullivan uses this comparison to deepen our understanding of their differences, suggesting Lydia's behavior might be harder to manage or comprehend due to its larger scope.