Simply so, should I run or save a download?
Run: Choose Run when you only need the download once. Save: When you want to keep whatever it is you've downloaded, choose Save. You can still run it, or whatever else you'd like to do with it, but you'll need to do that yourself. You'll also want to decide where, on your computer, to keep the file.
Secondly, what's the difference between open and save? If you choose to run the file (for some file types your choice will be "open" instead of run), the file is saved to a temporary folder on your computer and run or opened automatically. When you select save (sometimes only offered as Save As…) in response to a download, the browser simply downloads the file.
Also, what is the difference between a download and an app?
Download means to transfer a file. You are transferring the file to your phone. Install means to set it up and configure it, so that it works properly and can be opened. "download" is the app/software you do not have on your device like your phone or computer, but you want to have it, so you have to download it first.
Does downloading or installing come first?
When you download something like a program, what your computer must first do is retrieve a copy of all of the files that make up the program from the server on which the download is hosted, once this process is complete, your PC will then install the program by moving all of the relevant files in the downloaded folder
