Here is a good side on shot that shows the different window arrangement on the first and only O34 hull built by Pacific Boats. Not wildly different, but different. Otherwise from the pictures there isn't much obvious on the surface that distinguishes the PB from the Ericson. There are a few other cues, the black mast for one that make it likely to be a Pacific hull. That is one of the tells for the O911S. From what I recall Pacific used Ballenger spars and Ericson used Sparcraft masts and Kenyon booms. There are also slight differences in the shapes of the stern pulpits. Interiors are a bit different in how they are finished, but same layout.
Here is an interior shot:
