mips32el is for DM800se and mips32el-nf for the DM800

i mean DM800 not DM8000. The DM800 have a other CPU ...,.

No. These 3 boxes use mips32el; as @Hilfsbereit wrote, mips32el-nf is for DM800 (without se) only!

The file for dm8000 and dm7020 is on the feed

feed.newnigma2.to/daily/oe2.0/…4+cef47d8-r5_mips32el.ipk

all this boxes have the same cpu architecture: mipsel
but there is an other linux kernel used for the dm800hd in OE2.0

after a small change in the opkg conifg it is possible to install mip32el.ipk's on a dm800hd too, if all dependencies will be found on the dm80hd feed.
also binaries copied from a dm800se to a dm800hd will work if all needed dependencies are installed
it is also possible to extract a mips32el.ipk on a dm800hd wihtout opkg

so that's one of the reasons, why _all.ipk packages are build for OE2.0

only the kernel and all kernel-modules including the dependencies and some plugins with different dependencies must be used for the correct boxtype

but it is easier to handle for the user when different packages are build
mips32el-nf.ipk-> dm800hd
mips32el.ipk -> dm800se, dm500hd, dm8000, dm7020hd ...
all.ipk : for all boxtypes with mipsel cpu
boxtype.ipk: for this boxtype only
mipsel.ipk: <= OE1.5
powerpc.ipk: were used for dm7020si, dm600 enigma2 test images (powerpc cpu)

mipsel.deb: dm7080hd, dm52x, dm820hd
armhf.deb: dm900 UltraHD (arm cpu)
all.deb: all DreamOS boxtypes