this one is really a good question.
we had some discussions on all these as anand once explained difference b/t while and whereas. preat explained difference between instead of/rather than.
but those questions will give some insight for all these difficulties in the differences.
all these small things matter a lot.
but i am unable to search them now as i don't know their number.
i would like to suggest a search service in this site with some words, we can get the posts referring to it. but i am not able to find it.
can some body explains the differeces between them
while , whereas
despite of , despite
although , though
instead of , rather than
rather than , than
if some body puts this in verbal lessons it is very good for us to check again the concepts later.
i hope preat will help us for this.