There is a potential difference, but hard to determine if there is a real difference.
My optical out from my TV is 24b/48k, which is better than CD Quality. However, BluRay has the potential to be up to 24b/192k. Though just because the potential exists, doesn't mean they deliver it on the disc.
What are you sources? Computer? TV? Cable Box? Other?
If it is a DVD/BluRay Player, than I would suggest HDMI to the TV, and Digital Optical out of the TV.
Also, HDMI will cover all Multi-channel (5.1, etc...) format. In my case, the TV Digital Optical Out only supports Stereo (to the best of my knowledge).
So, it depends on what you are connecting where and why. I don't think we can make a constructive comment without more details.
Steve/bluewizard