精简版
Apache：出名比较早，09年左右是最流行的时期，功能强大，可以根据需求配置为基于进程，基于线程或者基于事件的，但是消耗内存较多，对硬件需求较高，内存是影响服务器性能的最关键因素，在VPS上不能很好的支持。
Nginx：属于后起之秀，近年来应用越来越广泛，主要特点是低内存消耗，可以很好的运行在VPS上，这是因为Nginx是基于事件的异步服务器，因此在收到新的请求之后，无需新建过多的线程。
Nginx并发数高，处理请求异步非阻塞，一个进程多个连接，而Apache是同步多进程，一个进程一个连接，属于阻塞型。
Nginx占用资源和内存小，高度模块化，配置简单，Apache的配置就相对复杂了。
Nginx适合处理静态文件和反向代理。
Apache的Rewrite功能更加强大，对动态页面支持更好，超级稳定。
Apache对PHP支持比较简单，Nginx需要配合其他后端使用，Apache的组件也更加丰富。
一般前端是Nginx，后端是Apache。
参考资料
[1]http://4921679.blog.51cto.com/4911679/1192611
[2]http://www.cnblogs.com/huangye-dream/p/3550328.html
完整版
Both Apache and nginx(pronounced “engine-x”) are free, open-source, cross-platform web servers.
The Apache HTTP Server, commonly referred to asApache, is a web server notable for playing a key role in the initial growth of the World Wide Web. [...] In 2009 Apache became the first web server to surpass the 100 million web site milestone. [...] Since April 1996 Apache has been the most popular HTTP server on the World Wide Web. As of March 2009, Apache served over 46% of all websites and over 66% of the million busiest.
nginx is noted to be a good server for sites that need fast, efficient reverse proxies [1], [2], [3]or fast, efficient serving of static content [4]. It is acclaimed for having low memory usage and is recommended for sites running on a VPS[5].
Architecture
Apache is a flexible server which can be process-based, thread-based or event-based as determined by the MPM used, while nginx is an event-based web server.
Nginx and Lighttpd are probably the two best-known asynchronous servers and Apache is undoubtedly the best known originally process-based server. The main advantage of the asynchronous approach is scalability. In a process-based server, each simultaneous connection requires a thread which incurs significant overhead. An asynchronous server, on the other hand, is event-driven and handles requests in a single (or at least, very few) threads.
While a process-based server can often perform on par with an asynchronous server under light loads, under heavier loads they usually consume far more RAM which significantly degrades performance. Also, they degrade much faster on less powerful hardware or in a resource-restricted environment such as a VPS.
Features
Like Apache, Nginx has all the features you would expect from a leading Web server:
- Static file serving.
- SSL/TLS support.
- Virtual hosts.
- Reverse proxying.
- Load balancing.
- Compression.
- Access controls.
- URL rewriting.
- Custom logging.
- Server-side includes.
- Limited WebDAV.
- FLV streaming.
- FastCGI.
It is stable, secure and very easy to configure, as you will see later in the article. However, the main advantages of Nginx over Apache are performance and efficiency.Whether you are looking to get the most out of your VPS or are attempting to scale one of the largest Web sites in the world, Nginx may be the best tool for the job. It's fast, stable and easy to use.
According to the Wikipedia article "Comparison of web servers", Apache has the following extra features compared to nginx:
- administrative console
- .htaccess
I mentioned earlier that nginx isn’t very suited for shared hosting. You might think that if you let nginx handle just static files while proxying non-existing files and dynamic files to Apache then you’ll be good. This isn’t quite the case, though. As an example, consider basic authentication, if you want to have basic authentication on a static file then you will need to add it in the nginx configuration, and users cannot do this without having to reload the configuration file. If you allow them to change it and reload it then they can make a mistake and ruin it for everyone.
— [6]
Performance
Nginx is faster at serving static files and consumes much less memory for concurrent requests. Because Nginx is event-based, it doesn't need to spawn new processes or threads for each request, so its memory usage is very low.
Wordpress.com has found nginx to be the only load balancer able to handle 8000 live traffic requests per second.[7]
The only solution I know of that's extremely high performance that offers all of the features that you want is nginx [...] I currently have nginx doing reverse proxy of over tens of millions of HTTP requests per day (thats a few hundred per second) on a *single server*. At peak load it uses about 15MB RAM and 10% CPU on my particular configuration (FreeBSD 6).
Under the same kind of load, apache falls over (after using 1000 or so processes and god knows how much RAM), pound falls over (too many threads, and using 400MB+ of RAM for all the thread stacks), and lighty *leaks* more than 20MB per hour (and uses more CPU, but not significantly more).
— Bob Ippolito , TurboGears mailing list, 2006-08-24
Ease of use
Configuration Tools [of nginx] is a cinch and deployment was easy as pie.
[nginx] is stable, secure and very easy to configure, as you will see later in the article.
— Nginx: the High-Performance Web Server and Reverse Proxy , Linux Journal, September 2008
We were using Pound for load balancing at Justin.tv until today. It was consistently using about 20% CPU, and during spikes would use up to 80% CPU. Under extremely high load, it would occasionally freak out and break.
We just switched to Ngnix, and load immediately dropped to around 3% CPU. Our pages feel a little snappier, although that might be my imagination. Not only is the config format easier to understand and better documented, but it offers a full webserver's complement of functionality.
Popularity
In 2009 Apache became the first web server to surpass the 100 million web site milestone. [...] Since April 1996 Apache has been the most popular HTTP server on the World Wide Web. As of March 2009, Apache served over 46% of all websites and over 66% of the million busiest.
Apache's web server market share is increasing again since early 2010, and Nginx has been more or less stable for a while now (since late 2009), according to Netcraft web server surveys for July 2011.
External Links
本文转自ZH奶酪博客园博客，原文链接：http://www.cnblogs.com/CheeseZH/p/5168360.html，如需转载请自行联系原作者
