The word childish is best utilized to express disapproval of someone's behavior that resembles that of a young child rather than an adult. It's especially apt when pointing out actions or mannerisms that society expects a person to outgrow. You might deploy this term when discussing someone's inability to manage their emotions or when they are being unreasonable or tantrum-like.

Use the term childlike to highlight qualities like innocence, simplicity, or openness that are reminiscent of a child's way of viewing the world. It's a word that celebrates the retaining of youthful virtues without any negative judgment. Childlike is most appropriate when complimenting an individual's capacity to appreciate life's simple joys or their genuine curiosity and excitement.

Although childish and childlike originate from the same root, their implications differ profoundly. Childish denotes immaturity and negative behavior associated with children that is unsuitable for an adult, while childlike celebrates the endearing traits typically ascribed to children, such as purity and a sense of awe. Understanding the distinction between these terms is key to using them correctly and conveying the intended message.