Those are pretty similar models with subtle differences in the details.
The Professional is closer to the classic Strat sound with single coil pickups & close to standard controls. Also it comes with a standard C profile neck which is a bit smaller than D, better for smaller hands.
The Ultra has the noiseless pickups, upgraded electronic controls & D neck.
I have a Strat with the N3 noiseless set, they are excellent. Definitely lose a little bit of the high treble end of the spectrum, but well worth it for the hum cancelling. Of course I'm used to that having put Dimarzio HS-3s and 4s in all my Strat for decades. I find it essential for any kind of gain tone. For clean tones I still have other Strats with standard single coils when cancelling that 60Hz hum doesn't matter as much.
Having said all that, I'm pretty sure you can get all those things as options (neck profile, pickups, electronics) on either model. And often you'll find a better deal if you look around guitar stores for sales & used models.
No matter what you do, make sure to try before you buy. Play lots of Strats until you find one that really feels & sounds good to you. Have fun gear hunting!
Thanks for this very helpful breakdown. I was surprised that the C shape neck would be smaller than the D. I’d been led to understand it was the other way round. I’ve got to say I’m kind of hoping that, when I try them out, I get on with the Ultra and that it’s sound is sufficiently distinct from my Les Paul because I’m definitely drawn towards the locking tuners and the noiseless pickups. Having said that, would a decent noise gate resolve the Pro II’s hum enough for gain tones?
