Can't compile loader in visual studio code

Hi.
I'm using the loader in Vs code with angular 4; I follow the starting guide (I'm new to webpackage, vs code, and so on) but to get it working I had to change all imports (i.e. from @import 'variables'; to @import '_variables.scss';); while are there these differences between file names? I get it working at last but my collegue can't download the package and get it working.
Thank you.