so in the 101 course you have a section Called How to get Babylon.js, but the problem is what version show use on my website? and what each version does? and what is the difference between them?
To keep the total file size of your project low then use the version babylon.js which has been minified. This gives exactly the same facilities as babylon.max.js which is the readable form. When you are beginning this will probably give you all the facilities you need. However BabylonJS offers more such as an inspector, loaders, GUI etc. If you need any of these you can load them as well as babylon.js.