Opportunist, longer blade, flat grind, stud (one side only), liner lock, wood, more wharncliffey, no clip
VG10 in the Viele, S30 V in the Opportunist.
Both are dressy. I like the longer blade of the Opportunist as well as the less belly. However, many like more belly on their blade than I do. I also prefer a flat grind to a hollow grind.
After all the talk of an eccentric stop pin, the Opportunist actually has one. Each facet of the pin is at a different distance from the center of the pin. You can adjust your liner lock for wear with it. I haven't tried that feature.
You probably have a better indexing and a bit of guard in the finger cutout for the Opportunist. In these knives, that shouldn't matter, but the argument is there to be made.
I own an Opportunist. I think it's prettier than the Viele and I use it for more formal occasions. It's not an EDC for me. The main thing I don't like about the Opportunist is the little pointy hump on the blade spine. It's just wrong for a blade that is otherwise so wharncliffe. It's sort of at the point a thumb ramp would be and is probably what the design is there for, but it breaks up the lines and isn't necessary to the blade IMHO.
I wouldn't want either as an EDC. I don't trust liner locks that much. But I explained why I like the Opportunist.