The 468 II manual download finally finished from China, glacially slow, I had given up.
And you're right, for unknown reason, there is no usual guide number chart in it.
So it just says GN 33 (meters), which is GN 108 (feet), so GN 33/108 (m/ft). We are not told for which zoom this applies, so we still do not know anything. The modern trend is to advertise the maximum number for longest zoom. We do need the chart.
The YN565EX manual chart shows GN 53/174 for 80 mm zoom (zooms to 105 mm),
and the SB-700 shows GN 35/116 for 85 mm zoom (zooms to 120 mm).
So if assuming GN 33 is for maximum 85mm zoom, then for FX, that implies the 468 II is 1.37 stops weaker than the 565, and barely weaker than SB-700 (at least at 85mm zoom). One stop less is half power, so that is a lot, and it would seem noticeable for most bounce. I am just guessing about the meaning disclosed however... they did not say.
The
http://hkyongnuo.com site does say of the YN565:
2), TTL Flash with very powerful guide number
GN58 @ ISO100, 105mm, support TTL, M, Multi mode
I think that would influence me today. It is powerful. The YN565 GN at 24mm is 28/92, which in tests, performs essentially same as (as good as) the SB-800 which says 30/98, and which is saying a lot.