BrickLink Stud.io is a spiritual successor to Lego Digitial Designer, a Lego built computer-based design tool which allowed users to build their own Lego creations from home and pay for the parts needed for their construction to be shaped to their home if they wanted. This program no longer supports the purchasing aspect and has not been updating pieces and so BrickLink Stud.io is a better alternative to me.
BrickLink is a third-party seller of Lego pieces who designed and built BrickLink Stud.io after Lego Digital Designer. It has some differences such as the fact that you can model any piece in any color ever produced by Lego whether or not the Lego piece is actually manufactured in that color or not. The sets built here are going to be a combination of Lego designs as well as my own creations and potentially community creations. If the title features a string of numbers, then it is design created by Lego
If there is no string of numbers then it is my own design or a design created by the community which Bricklink Stud.io allows you to share. With every design, the Stud.io file will be attached, two different render types (photoreal and pov-ray) will be attached in some combination of .npg and .png file type and if it is a Lego design or if I am able to do so easily enough, a BrickLink Stud.io created design booklet in .pdf form will also be attached.