Well, you made this super easy by giving me a location. Spotted Owls are West Coast owls from Canada through Mexico, so you've got a fine Barred Owl there.
But let's say we didn't have a location. How would we figure this out? Let's take a look at our 2 suspects side by side:
Now our friend the Barred Owl is given his name for that beautiful vertical barring on its belly. You can't see that at all though in your pic, and even in the first example it's kinda scrunched up and not super identifiable. Second pic it's very obvious though. But that wouldn't help you here, so what else do we see?
Look at those sweet faces. Both are adorable, but one owl has a pale face and one has a dark face. Spotted Owls have a darker base coloring, so they'll have a dark facial disc compared to the Barred. Now of course we have coloration in various degrees, but even when I try to find a darker faced Barred and a lighter faced Spotted, it takes a little longer glance, but I think you'd still have a good shot at getting it right if you gave it a solid look. Even here the Barred "eyebrows" don't stand out as much because the face is still much closer in base color to the white brows.
Again, whitish base for Barred lets those white stripes shine. Brown base for Spotted makes them more off white, and the back is, much like the front, more spotted than striped.
So all signs point to your guest being a Barred Owl!
The 2 get mistaken frequently, and with the hybrids it blurs the lines even more. That is one of the main concerns about the project to shoot the Barred Owls and hybrids to protect the Spotted. With Spotted Owls being so reduced in number already, killing just one by accident can be a huge loss.
So you did not get a visit from a rare owl, but it's still superb! I'm so glad you shared it and we got to learn a lot!