The vector file or source file is an editable and resizable file. It’s usually deliver as .ai, .eps, .svg or .psd. If you order vector file you’ll get only the .ai or .eps or .svg. If you order source file you’ll get all of the 3 + .psd file. There’s no difference, unless the variety of files.

There are many answers you can find through google actually but there is simple analogy you can easily to understand; having a vector file or source file is important. It prove your ownership of the logo and it’s like you’re having a key for your own home.

Profile picture and banner/cover design for your social medias e.g facebook, twitter, etc.