"Chants work on magical words, predominantly - wanded magic does often includes incantations, though incantations are secondary to the wand and can more easily be omitted. Incantations provide specificity - important when you're first learning, and your wandwork might not be precise - as well as focus and deliberation. They're almost always short and sometimes only tangentially tied to the spell's effect. An incantation is a name of a spell, as much as anything, which is why a lot of spell incantations aren't actually in grammatically valid Latin - they don't need to be."
"Chants are different. By default, a chant is a long, rhythmic description of what you want to happen. Many are designed to be repeated, and many chant traditions are innately rooted in the idea of group practice. There's well defined chants, which beginners should stick to, but it's much easier to innovate once you get a feel. Chants usually aren't the sort of things we'd actually say when talking - they're a lot more like poetry, with different traditions often representing different poetic norms. Standard American practice emphasizes sung chants, in English, with distinct meters and often rhymes. It encourages but does not require group practice, and also encourages the incorporation of symbol and movement - such as specific clothing, dances, ritual baths before major workings, the use of candles, and the like."
"Talented practitioners can use shorter chants for the same effect, and it's actually possible to omit speaking entirely, though it's hard to perform without any movement or use of symbolism - a chant is a communication, so you could use sign language without much difficulty, but it's not a meditative tradition - there must be an attempt to project meaning outward."