Yes, the hybrid will certainly be different, and likely any 2016 may be too.
There's a couple old threads here on horn replacement.
I'll be looking at this too if I ever see the car. Worst case if the OEM horns are inaccessible you can cut the wires and run them to your new horns. Biggest problem is getting at them to swing a wrench.
Sounds like you only replaced one of the horns, or one didn't have power, I put the Freeway Blasters on my 2006 V6 Rav4, they were a bit louder than the El Grande, my wife says both are too loud, she likes the beep-beep on her Prius! :laugh