Block count differences between "df" and "dd" - why?

[David Tonhofer, m-plify S.A.]

This should be easy: Does anyone have an explanation for
the block count differences regarding my /dev/sdb1:

"df" says:   /dev/sdb1  has   194442 1K-blocks
"dd" says:   /dev/sdb1  has 401562+0 records of 1/2K, thus more than "df" syas
"fsck" says: /dev/sdb1  has   200780 1K-blocks, 1 less than "dd" says

I would think that fsck does not consider the first block of the
partition, which would explain the difference between fsck and dd.

But why does "df" see a smaller partition than "dd"?


-- David