I am a self proclaimed ink-o-phile. I can see the nuances in inks that other people would never even notice. But these two inks were really hard for me to tell apart. And let me just say that by blowing up the pictures you can see the differences much more clearly. In person, even with the page close to my face, I could barely see ANY difference at all. The pictures blown up on a computer screen is the first time I can really see them are different at all.
I do several lines of writing to find the places two inks differ. In written text, it looks like 334 is a bit darker.
But only sometimes. See this? #34 looks about the same darkness but a bit more yellow in undertone.
The colour swaths are usually where the subtle differences show through, but with these two inks, it actually confused me more.
In this moment, the shaded areas of #34 look darker, but the lighter areas seem more similar to #28 than they did in the last picture. Still just a tiny stitch more yellow but BARELY.
More comparison shots in my comparison album here.