confusion with some `git reset` commands

From: Arup Rakshit <aruprakshit@rocketmail.com>
Date: Dec 16, 2014, 18:39 UTC
Message-ID: <2055441.uOK6yH3IMG@linux-wzza.site>

Hi,

>From the command help I see -

[arup@to_do_app]$ git reset -h
usage: git reset [--mixed | --soft | --hard | --merge | --keep] [-q] 
[<commit>]
   or: git reset [-q] <tree-ish> [--] <paths>...
   or: git reset --patch [<tree-ish>] [--] [<paths>...]

    -q, --quiet           be quiet, only report errors
    --mixed               reset HEAD and index
    --soft                reset only HEAD
    --hard                reset HEAD, index and working tree
    --merge               reset HEAD, index and working tree
    --keep                reset HEAD but keep local changes
    -p, --patch           select hunks interactively

But I am looking for any differences -

a) git reset --soft and git reset --keep b) git reset --hard and git reset --merge

-- 
================
Regards,
Arup Rakshit
================
Debugging is twice as hard as writing the code in the first place. Therefore, 
if you write the code as cleverly as possible, you are, by definition, not 
smart enough to debug it.

--Brian Kernighan