difficult

Compared meaning: difficult to do or deal with (adjective).

比较义项：困难的，不容易做到或应付的（形容词）。

• challenging

  Emphasizes that a task tests or stretches someone's abilities in a stimulating way; often used approvingly, suggesting effort leads to growth rather than mere hardship.

  强调某件事以激励性的方式考验或锻炼一个人的能力，常用于褒义，暗示努力会带来成长，而不只是艰辛。

  She took a challenging new role that pushed her to learn skills she'd never used before.

  她接受了一份有挑战性的新工作，促使她学习了以前从未用过的技能。

• tough

  Suggests a difficulty that demands endurance, toughness, or emotional strength; more informal and often implies hardship or strain rather than an opportunity for growth.

  暗示这种困难需要毅力、坚韧或情感上的力量来应对；语气更口语化，常暗含艰辛或压力，而不是成长的机会。

  Losing his job right before the holidays was really tough on the whole family.

  在假期前失业对整个家庭来说真的很艰难。

• hard

  The plainest, most common word for difficult; neutral and informal, used in everyday speech and fixed expressions without any special connotation.

  是表示“困难”最普通、最常用的词；语气中性、口语化，常用于日常表达和固定搭配中，没有特殊的感情色彩。

  I find it hard to say no to free food.

  我发现很难拒绝免费的食物。

• difficult 本词

  More formal and neutral than hard; common in written or professional contexts, describing a task or situation as requiring much effort, without emotional coloring.

  比 hard 更正式、更中性，常用于书面语或正式场合，描述某件事需要付出很多努力，不带感情色彩。

  The committee found it difficult to reach a unanimous decision on the budget.

  委员会发现很难就预算问题达成一致意见。

All four mean difficult, but differ in tone. Challenging is positive: a task that tests and builds skill. Tough is informal, stressing hardship and endurance. Hard is the plainest, neutral word. Difficult is more formal than hard. Tough's sense of physically strong is not compared.

这四个词都可以形容“困难的”事情，但语气和用法不同：challenging 带褒义，强调考验并锻炼能力；tough 更口语化，强调需要毅力去承受艰辛；hard 是最普通、最中性的日常用词；difficult 比 hard 更正式，多用于书面或正式场合。这里不比较 tough 表示“坚韧的、不易折断”的物理意义。

Compared meaning: hard to control or manage (adjective).

比较义项：难以控制、难对付的（形容词）。

• difficult 本词

  Difficult is a general, milder word for someone hard to manage or deal with; it doesn't necessarily imply bad behavior, and is common in neutral or formal contexts (a difficult child, a difficult client).

  difficult是较为温和、笼统的说法，指某人难以相处或难以管教，不一定意味着行为恶劣，常用于中性或正式语境中（如难缠的孩子、难缠的客户）。

  Her elderly father has become quite difficult since he moved in with them.

  自从搬来和他们同住后，她年迈的父亲变得相当难缠。

• unruly

  Unruly is stronger and more vivid, describing people (often groups, children, crowds) who are disorderly, noisy, and refuse to follow rules; it always implies bad behavior, not just being hard to deal with.

  unruly语气更强、更生动，用来形容人（常指群体、孩子、人群）无秩序、吵闹、不服管教，总是暗示行为恶劣，而不仅仅是难以相处。

  The unruly crowd pushed past security and rushed onto the field.

  不守规矩的人群冲破安保，涌上了球场。

Both can mean hard to control, but difficult is milder, just meaning hard to manage, as in a difficult child. Unruly is stronger, describing disorderly people, often groups or children, who won't follow rules. Difficult's other sense, not easy to do, is not compared here.

difficult和unruly在“难以控制”这一意义上接近，但difficult语气较温和，只表示难对付、难管教，未必涉及行为不端；unruly语气更强，专指行为无序、不服管教的人或群体。这里不比较difficult“不容易做到”的意思（如难度大的测试）。