The definition of "abugida" in WWS and Unicode *do* have differences.
Actually, they seem to have absolutely nothing in common, apart the entry
term...
WWS says that:
W.1) The basic characters of an abugida denote consonants followed
by a particular vowel;
W.2) Diacritics [applied to basic characters] denote the other
vowels.
Unicode says that:
U.1) An abugida is "special";
U.2) Many scripts of South and Southeast Asia are abugidas;
U.3) Scripts called "abugidas" are historically derived from the
ancient Brahmi script;
U.4) A comment about the etymology of the word "abugida".
Frankly, the Unicode definition sounds quite broken... I would say that U.3
is false (how about Ethiopic?), U.2 and U.4 are useless (U.4 perhaps even
incorrect), and U.1 is simply meaningless ("special" compared to what?).
The WWS definition corresponds to my understanding of the term and,
probably, to the understanding of many other people here. But notice that
Peter T. Daniels, the author of the definition and, it seems, inventor of
the term, negated clause W.2 just a few days ago on this very forum, so it
is not clear right now whether we should credit what the author says or what
he wrote...
Perhaps we should restart the discussion from here: do you, prof. Daniels,
confirm or withdraw clause W.2 above? If you withdraw it, do you think that
clause W.1 alone is enough to define an abugida, or would you add substitute
old W.2 with something new?