I find that the EST Genesis strobe-only notification appliance is literally the exact same but without the horn in it. Is there a difference?
Not really. I asked this exact same question. Both the horn/strobes and the remote strobes look the same and come with a speaker and the space you can look into it through it. Just the remote strobe doesn’t have a horn in it.
You’ll know it’s a remote strobe if there’s nothing shiny inside the grill, because the piezo had been removed.
Erm, if you knew this already, then why did you ask about it in a topic in the first place? 
Because I wanna show you a picture of what it looks like because most people don’t know what it is.