When using the Software application in Fedora, you will notice a Source drop-down in the top-right corner of some application pages. This option appears when Software has detected that the application is available from multiple software repositories.
To get started, lets open the Software application. On a fresh install, you can find Software by accessing Activities overview and then selecting Software from the dash shortcut:
Next, lets select a random application. In my example, I am going to pick Gnome Music.
In the top right corner, you will see a Source selection. Selecting this drop-down will reveal two options, "Fedora" and "Flathub". These options indicate the this app is available from Fedora's application repos as well Flathub. If you have not already, you can add Flathubs repos here: https://flatpak.org/setup/Fedora/. Note: many of the applications in Flathub include non-free source code.
After selecting an option from the drop-down, you can verify the application Version and Source from the Details section. You may want to compare the two sources to determine which source provides the newest version. However, in general it is best to select the application from the Fedora registry as you can take comform knowing it is maintained by the Fedora Project.
In the image above, you will also see the "Sanboxed" attribute. This is an attribute of flatpaks and a primary reason to select flatpaks over traditional packages.
If you are using Silverblue, all apps in Software should appear as flatpaks. However, if you are using a traditional linux system like Fedora Workstation, you may notice another option in the Source drop-down to indicate an RPM package:
The user should note that RPMs are not sandboxed: