GXF and GXK Series of Blue Note reissues by King Record are identical (apart from Blue Note Unissued Master series and some other concept series like Jazz Guitar Album series).
Many titles present in GXF series are also present in GXK series, popular titles like Art Blakey Moanin', Paul Chambers Bass on Top and so on.
Some Jazz collectors say GXK sound better than GXF. Some say GXF sound better than GXK...I used to think, GXK sound better than GXF.
I now concluded that there is no difference between GXF and GXK in terms of sound. Both sound great, really.
What about the pressing quality? sleeve quality?
Well, I think the same. Again, both quality is superb.
OK, now OBI. Any difference?
Yes! minor difference though...
GXF OBI has a title in Japanese, saying
1800 Immortal Blue Note Series Limited Edition!
1800 means the price they put at the time of release, 1800 yen.
GXK OBI has a title in Japanese, saying
Blue Note 150 Masterpiece Series
The price was increased to 2300yen. They also put a round logo that shows commemoration of 100 year anniversary of the analog records, 1877 to 1977.
Another difference. The inserts. With GXF, they put 2 inserts. One is a normal liner note by one of the jazz critics in Japan, the other is a list of Blue Note titles by artists from A to Z.
Although they are minor...these are the differences between GXF and GXK.