What are these kind of assemble-able "Erector" sets generally known as or called?
Those are usually just called T slot aluminum extrusions.

The 80/20 one is by far the most common style but now there are alternative standards created in the past few years such as

MakerBeam http://amzn.to/2h2F9hq

OpenBeam http://amzn.to/2h1Tyui

80/20 profiles
10 series   1" 
15 series   1.5"
20 series   20 mm  
25 series   25 mm  
30 series   30 mm  
40 series   40 mm  
45 Series   45 mm


Maker Beam 10 mm


Maker Beam XL 15 mm


Open Beam 15 mm