对比文(comparison and contrast)是一种对两个或多个人或事物进行比较或对照以揭示其异同的篇章类型。比较(to compare)的目的是展示事物的相同点，对照(to contrast)则为了指出其不同之处。由于人们在日常生活中总要对各类事物加以区别、识别或选择，他们也因此必须对存在于周围世界的人或物进行比较和对照，因此对比文是一种极其常见的篇章形式。
为了使文章明确清晰，作者一般对相同类型的人和物的，可比特征进行比较和对照。也就是说，一篇文章往往将--辆福特汽车和一辆丰田汽车进行对比，而很少拿一辆汽车与一间房子去比，因为前者可对一些共有的特征进行比较和对照， 从而找出它们之间的异同之处，后者却缺乏可比性。所以，对比文的内容。即比较或对照的对象往往同属-个大的范畴。
示例分析
有的对比文只对事物进行比较，如下例：
1. 比较 (Comparison)
A Buick and a Cadillac, both built by General motors,are alike in many ways. A Buick, which measures over 200 inches in length and weighs over 3,000 pounds, is large and holds the road well. A Cadillac is similar in length and weight. Like a Buick, a Caclillac gets relatively low gas mileage compared with smaller economy cars made by the same manufacturer. The Buick provides an unusually comfortable ride especially on cross-country trips on the highway, as does a Cadillac . And both cars enjoy a certain status as a luxury automobile.
此文加以比较的是美国通用汽车公司制造的两种汽车．正文前3句分别列出了它们相同的特征，即车身大小、耗油量、舒适程度和等级等方面的一致性。最后一句是此段的小结，说明这两种牌号的车都属豪华型高级轿车。
下面我们来读一段对照文章。
2．对照(Contrast)
The twins are different as two people can be. Sally, who is always hoping someone will have a party, has black hair blue eyes, and an outgoing personality. She wants to be an
actress or a popular singer. Susan, more serious and studious. has blond hair, brown eyes ,and a somewhat shy man nor. Since she has done well in all her classes in graphic arts
and math, She plans to become an architect or an engineer.
3. 对比 (Mixed comparison and contrast)
Most Americans would say it is not really possible to establish an ideal society. But time after time, a small dedicated group of people will drop out of the mainstream of
American society to try once more, to live according to the group's concept of an ideal society most of these groups have believed in holding their property in common. Most have
used the word "family" to refer to all members of the group Many of these groups, however, have differed widely in their attitutes toward sex and marriage.
此文说的是一些小的社会群体。它们有相同之处，即都认为财产归大家所有，并认为各自的群体是一个大家庭；不同的是，这些群体对性别和婚姻的看法却不尽一致。
上述三篇对比文不仅侧重点不同--有的只有比较，有的仅有对照，有的既比较又对照，而且在内容安排上(即结构上)差异也很大。例(1)的信息或内容安排是这样的：
中心思想,: A Buick and a Cadillac are alike in many ways
Buick (或 subject])
1. 车身 (length e width)
Cadillac (或 subject2)
Buick
2. 油耗 (mileage)
Cadillac
Buick
3. 舒适 (Comfort)
Ccadillac
Buick
4. 等级 (Status)
Cadillac
此结构的特点是两者的比较按不同的特征依次展开，因此被称为特征结构模式(the characteristics pattern)。此结构可归纳为以下形式：
主旨或主题 Introduction (includes thesis, sets up comparison or contrast)
subject (1)
特征 Characteristic 1
subject (2)
subject (1)
特征 Characteristic 2
subject (2)
subject (1)
特征 Characteristic 3
subject (2)
subject (1)
特征 Characteristic 4
subject (2)
结论 Conclusion
例(2)与以上模式不同，文中的对比是分块进行的，即先说Sally，后谈Susan，两块文章的对比范围却是相同的，此文的内容分布形式为：
中心思想: The twins are as different as two persons.
第一部分 (Block 1): Sally:
1. appearance
2. personality
3. future career
第二部分 (Bock 2): Susan:
1. appearance
2. personality
3. future career
Introduction (includes thesis, set up comparison or contrast)
Characteristic (1)
对比形象 Subject 1 Characteristic (2)
Characteristic (3)…
结论 Conclusion.
中心思想: "... people drop out of the mainstream of
American society…o live according to the
group's concept of an ideal society"
Block 1
(1) common property
Comparison
(2) group as "family"
Block 2
Contrast: attitudes toward sex and marriage
4. Types
主旨句： There are only two types of people in the world Type A and Type Z, and they are
in sharp contrast in many ways.
1. catching a To catch a plane early plane catchers plane Type A, pack their bags at least a day in advance ,and they pack neatly. If they're booked on a flight that leaves at four in the afternoon, they get up at 5:30 that morning. If they haven't left the house by noon, they're worried about missing the plane.
Late plane-catchers, Type Z, pack hastily at the last minute and arrive at the airport
too late to buy a newspaper.
2. reading a What do you do with a new book? Type book A read more carefully and finish every page,even though it isn't any good. Type Z skim through a lot of books and
are more apt to write in the margins with a pencil.
3: eating Type A eat a good breakfast； Type Z breakfast grab a cup of coffee.
4.- turning off Type A turn off the lights when leaving lights a room and look the doors when leaving a house. They go back to make sure they've locked it, and they worry later about whether they left the iron on or not. They didn't. Type Z leave the lights burning and if they lock the door at all when they leave the house they're apt to have forgotten their
keys
5： seeing the Type A see the dentist twice a year, have doctor annual physical checkup and think they may have something.Type Z have been meaning to see a doc
6: using a Type A squeeze a tube of toothpaste toothpaste from the bottom, roll it very carefully as they use it and put the top back on every time. Type Z squeeze the tube from the middle, and they'v lost the cap under the radiator.
7: other Charac- Type Z are more apt to have some Type teristics A characteristics than Type A are apt to have any Type Z characteristics.
8: marriage Type A always marry type Z;Type Z always marry Type A. conclusion Different as they are from each other,Type A and Type Z get on with each other quite well by Andy Rooney
(from Patterns of Short Prose Reader)
此文有主旨句，有正文，有结论。在正文中作者就八个方面对Type和Type Z这两类人进行了全面的对比，指出他们各自在乘飞机、读书等方面不同的行为方式。
