都可以用来表示询问或建议，但是用法还是有一定区别：
1.what about …
What about …，用来提出询问或建议，意为”…怎么样“，例如：
about介词后接名词性的词项：
What about my copier? Can you get it going again?
我的复印机怎么样了？你能把它修好吗？
But what about those growing waistlines?
但是那些越长越粗的腰围怎么办呢?
What about pizza? Can everyone agree on that?
披萨怎么样？大家都同意吗？
What about a movie on Saturday? Are you free?
星期六去看电影怎么样？你有空吗？
What about making a sudden turn to avoid a dog?
为躲避一只小狗而急转弯怎么样?
What about going out with me tomorrow?
明天和我一起出去怎么样？
What about dinner at my place?
到我家吃晚饭好不好？
How about [=what about] driving to the coast for the weekend?
周末开车去海边怎么样？
What about [=how about] coming with us?
和我们一起去怎么样？
2.what if …
What if …，用来表示询问或建议，意为“如果…怎么样呢”，“如果……怎么办”可用一般现在时或一般过去时，if是连词后接从句；例如：
What if the train is late?
火车要是晚点会怎么样呢？
What if aliens did exist? What would that mean for society?
如果外星人真的存在呢？这对社会意味着什么？
What if the parachute doesn't open?
降落伞打不开怎么办？
What if she forgets to bring it?
要是她忘记带来，会怎么样呢？
What if this doesn't work out?
如果这个不行怎么办？
What if he was going to die!
如果他快要死了该怎么办？
What if he got a guilty conscience and brought it back?
要是他觉得内疚，把东西拿回来了怎么办？
But what if the government takes no heed?
但如果政府不理会该怎么办呢？
What if Spain reacts to the similar economic pressures which are appearing over there?
西班牙要是对类似于那里正在出现的经济压力做出反应该怎么办？
What if it rained and then froze all through those months?
要是那几个月一直又下雨又冰冻怎么办？
What if relations between you and your neighbour have reached deadlock, and their behaviour is still unacceptable?
如果你和你的邻居已闹僵了，而他们的行为还是令人难以接受，那怎么办？
What if anything should happen to the child?
万一这孩子出了差错怎么办？
What if something should happen to her?
万一她有个好歹，这可怎么办？
What if they talked a long time about a painting you weren't that interested in?
如果他们花很长时间谈论一幅你不感兴趣的画怎么办？
高考真题- 2018 天津
What if the family had simply left the cat behind?
如果家里人把猫给忘了呢? 高考真题- 2015 重庆
What if that dream comes true?
如果梦想成真呢?中考真题- 2019 衡阳