/**
 * Finds and returns the differences between two objects `a` and `b`.
 *
 * @param {Record<string, any>} [a] The first object to compare.
 * @param {Record<string, any>} [b] The second object to compare.
 *
 * @returns {Record<string, any> | undefined} An object containing the differences between `a` and `b`, or undefined if `b` is null or undefined.
 */
export default function deepCompareObjects(a?: Record<string, any>, b?: Record<string, any>): Record<string, any> | undefined;