In the categorization of writing systems, alphabets (such as Latin) encode each phoneme as a distinct letter; abjads (such as Arabic) encode only consonants, with vowels as optional diacritics; abugidas (such as Indic scripts) primarily encode consonants but mark vowels in some systematic way; syllabaries just encode each syllable as a unique glyph without any systematic modification; and logographic systems don't have any systematic phonetic component (although they usually are influenced by phonetics, e.g., the rebus principle of diagramming abstract concepts by use of homonyms).

Sequoyah had access to an English-language Bible, so although he couldn't read the Latin text, he used several letters as inspiration for Cherokee, which is why you see Latin characters that correspond to completely different sounds.