The following is for Blender 2.79
It seems Blender doesn’t have a smooth preview function in it akin to what Maya has using the 3 key. Rather you have to add a subdivision modifier to the geometry in order to get a smooth preview of the mesh in the viewport - This will also apply the smoothing to the geo in the render. The nice thing about this is you can easily control both of these values in a clearly defined area, as apposed to in Maya where you have to dig down into the objects shape node to adjust the amount of previewed subdivision levels(not that you need to adjust that often). Thankfully I managed to find some shortcuts to easily adjust the subdivision levels on the fly on a reddit post(https://bit.ly/2x9RXrm). The shortcuts are as follows - Ctrl+0/1/2/3(The subdivision levels will be adjusted for the selected object depending on the number pressed). This is handy, however it would still be nice if they consolidated this to a one key shortcut solution perhaps with and default set up of 3 subdivision levels for both the view port and render.