ediff refinement issues

[Samuel Wales <samologist@gmail.com>]

Ediff lets you show individual words that are different, and
it also shows you when there are only whitespace differences
in paragraphs.

I am having issues with each of these two related features.

  1) When there are only whitespace differences in normal
     paragraphs, such as by refilling, ediff works well.  It
     says there are only whitespace differences and does not
     highlight any words.

     However, if the paragraphs are commented (for example,
     with ;;; in elisp or # in shell), it highlights the ;;;
     or the #.  it also sometimes highlights words as a side
     effect.

     I want ediff to show refilled commented paragraphs as
     only having whitespace differences.

  2) When I change a date like 2011-01-01, ediff highlights
     the entire date even if I only changed one part of it.

     For example, if I change 01 to 02, it will still
     highlight the entire date.

     I want it to show only the part I changed.


There are variables ediff-word-1 ediff-word-2 ediff-word-3
ediff-word-4 that are supposed to customize this.  I tried
them in various ways and they didn't produce the results I
wanted.

How do you use those variables to do this?

Thanks.