Construction can refer to all types of building, often with the idea of building an entire project from the ground up. Erection is used more in the sense of making something upright. Installation is when something additional is added to a building or a room, e.g. a new bathroom installation, an installation of a new shower and bathtub in the bathroom, an installation of new windows, etc. Mounting is usually when something is attached to an existing wall, e.g. a mirror was mounted on the bathroom wall.

这都是名词，都是同义词，区分它们看其原对应的动词:construct, erect, install, 和 mount, 可以看出其对应名词强调的区别意义:construct 主要是指施工(建造楼房，公路等)，erect主要是强调"竖立起来的东西的"建造"有"搭起"架起来含义。install 主要强调安装"机器设备或者程序，mount 主要强调安装过程需要"牢固固定"，例如天花板上装电扇。 但是，毕竟属于同义词，假如不知道如何区别，无论哪一个都行，由于有具体被安装的"东西"(做动词安装的宾语)，不会造成误解，但会造成用词不当。名词的情况也是如此(关注这些名词所连带的短语也不会误解但也会造成用词不当，其实是小问题)