nginx or Apache HTTP Server that's the question. The best choice depends on what it needs to serve. In general, Nginx performs better with static content, where Apache and Nginx score roughly the same when it comes to dynamic content. Since most webpages and web-applications use both static and dynamic content, a combination of both platforms may be the best solution.
Since both webservers are easy to deploy and free to use, setting up a performance or feature comparison test is no big deal. This way you can see what solutions suits your application or content best. Don't forget to look at other aspects, like security, back-end compatibility (easy of integration) and manageability, as well.
A reasonably good comparison between the two can be found in the link below.
Using Nginx over Apache somehow saves a lot of resources. Unlike Apache, Nginx only uses the memory as and when required and that too less in comparison to Apache