Writing Systems of the World 7, Exercise 1: three types compared

Syllabary: one symbol per consonant-plus-vowel pair, and symbols that share a
consonant or vowel usually look unrelated. Example: Japanese kana (Chapter 4).

Abugida: the basic symbol is a consonant with an inherent vowel, and the other
vowels are marked by a sign or by changing the consonant, so related syllables
look related. Example: Devanagari (क, का, कि).

Alphabet: consonants and vowels are separate letters of equal status.
Example: Greek (Chapter 6).

(The Abugida article draws these contrasts. Remember the warning in the
chapter: the Ge'ez script is described as "laid out as a syllabary" yet
classed as an abugida, so the edges are not sharp.)