[UBIFS] Filesystem capacity

[Adam S. Turowski]

Hi,
Can anyone explain differences in filesystem capacity between jffs2 and 
ubifs?
Kernel 2.6.28
mtd3 29MB nor flash
mtd4 31MB nand flash
File created by dd-ing from /dev/urandom:
jffs2:
nor: 28361 kB
nand: 31200 kB

ubifs:
one volume created on mtd3
UBIFS: mounted UBI device 0, volume 0, name "root"
UBIFS: file system size:   28676736 bytes (28004 KiB, 27 MiB, 219 LEBs)
UBIFS: journal size:       1440384 bytes (1406 KiB, 1 MiB, 11 LEBs)
UBIFS: media format:       4 (latest is 4)
UBIFS: default compressor: LZO
UBIFS: reserved for root:  1417227 bytes (1384 KiB)

one volume created on mtd4
UBIFS: mounted UBI device 1, volume 0, name "data"
UBIFS: file system size:   31870976 bytes (31124 KiB, 30 MiB, 2008 LEBs)
UBIFS: journal size:       1603072 bytes (1565 KiB, 1 MiB, 101 LEBs)
UBIFS: media format:       4 (latest is 4)
UBIFS: default compressor: LZO
UBIFS: reserved for root:  1575089 bytes (1538 KiB)

nor: 26960 kB (I can live with that)
nand: 23552 kB (With that I cannot)

Any suggestions?

--
Regards,
Adam Turowski