Are the installation media for Windows 10 Home and Professional different?

Unfortunately Microsoft has pulled the 1511 update for the media creation tool, and I need that update so that the old Windows Professional key will be recognized and I don't have to perform an upgrade first before doing a clean install.

Microsoft only temporarily pulled the updated Media Creation Tool. If you really want to use the 1511 Media Creation Tool it still exists on the Microsoft servers here

You can still find the 1511 version of the media creation tool on various sites, I tried that but I only get the choice between the "Windows 10" and "Windows 10 N" editions. With the non-1511 tool directly from Microsoft I got also the choice for Windows Professional there.

You want to choose Windows 10. The 1511 Media Creation Tool would download a universal x86 x64 Windows 10 Home/Windows 10 Professional .ISO.

Are the installation media for Windows 10 Home and Professional actually different? Or can I install Windows Professional with a USB drive created with the "Windows 10" edition selected in the media creation tool?

The build 10240 Windows 10 Home and Windows 10 Professional .ISO files are indeed different. This is no longer the case with the 1511 .ISO. The updated .ISO file is a universal Home/Professional x64/x86 .ISO file.

There is one installer for both editions. Media creation tool puts now 3 editions in one installer: Pro, Home and Education. Windows automatically chooses one according to your serial key in BIOS or already installed Windows OS. You can force it to let you choose what you want to install by creating one file on your installation disc/USB drive.

Create ei.cfg file in sources directory on installation disc/USB drive, open it in any text editor (for example notepad) and paste this:

[Channel]
Retail

Result: