但有两个版本：
> Ubuntu 16.04 LTS – Xenial(HVM)
> Ubuntu 16.04 LTS – Xenial
两者之间的区别是什么？我应该选择哪一个使用Nginx的基本Web主机？
这两个图像适用于不同的实例类型.从Linux AMI Virtualization Types开始,您将了解这两种类型之间的区别.
HVM：
This virtualization type provides the ability to run an operating system directly on top of a virtual machine without any modification,as if it were run on the bare-Metal hardware.
PV：
Paravirtual guests can run on host hardware that does not have explicit support for virtualization,but they cannot take advantage of special hardware extensions such as enhanced networking or GPU processing.
在AWS EC2的文档中,亚马逊声称这两者之间没有显着的性能差异：
Historically,PV guests had better performance than HVM guests in many cases,but because of enhancements in HVM virtualization and the availability of PV drivers for HVM AMIs,this is no longer true.
所以只需选择HVM.
