Im not familiar with Substance, but in contrast to the UE4 Material editor, you can really create Materials from source with it. For example, if you take a photo from a wall and want to make a material of it, you need a real photo editor like gimp, photoshop or substance.
The UE4 Material editor is powerful as well but not meant to create materials out of raw photos.
If you really want to learn how to create materials and tileable textures, you should investigate in a software like substance or photoshop. You can afterwards add many effects to the materials inside the UE4 material editor.
If you only want to have nice materials for mapping, you can look for free textures and convert them with some simple tools into materials. Then, you only build them together inside the UE4 material editor. I used this way for my last map because it was easier and saved a lot of time. I used Gimp with a plugin to create the necessary normal- and bump maps