grin

Compared meaning: a smiling expression showing pleasure (noun).

比较义项：微笑／露齿笑（名词）。

• smile

  The everyday, neutral word for a pleased or friendly expression; may be gentle and closed-mouth, and does not necessarily show the teeth.

  日常、中性的词，表示令人愉悦或友好的表情；可以是温和的、不张嘴的微笑，不一定会露出牙齿。

  Her warm smile made everyone in the room feel welcome.

  她温暖的微笑让房间里的每个人都感到宾至如归。

• grin 本词

  A wider smile that shows the teeth, usually suggesting stronger amusement, excitement or mischief; more informal in tone than smile.

  一种更宽的笑容，会露出牙齿，通常表示更强烈的开心、兴奋或调皮情绪；语气比smile更随意。

  He couldn't help but grin when he heard the good news.

  听到这个好消息时，他忍不住咧嘴笑了。

Both words describe a happy facial expression, but they differ in strength and tone. Smile is the everyday, neutral word; it can be gentle and closed-mouth. Grin means a wider smile that shows the teeth, suggesting stronger feeling, and sounds more playful or excited.

这两个词都表示因高兴而流露出的表情，但程度和语气不同：smile是日常、中性的说法，可以是温和的、不张嘴的微笑；grin则指咧嘴大笑，通常会露出牙齿，情绪更强烈，语气也更随意，带点调皮或兴奋的意味。