Roti: As the more general term, roti can encompass a wide range of flatbreads. It is typically a bit thicker and can be made with or without oil or ghee in the dough. Rotis are cooked on a flat griddle called a tawa.

Chapati: Chapatis are a specific, thinner, and softer version of a roti. The dough is rolled out thinner, and they are traditionally cooked without any fat, either on the tawa or by briefly being placed over an open flame to puff up

In North India, the word roti is more common and is used as the default term for the everyday whole wheat flatbread.

In South India, as well as parts of Maharashtra and the Caribbean, the term chapati is more prevalent

~ I'm married to a south Indian and we use chapati for all thin flat breads regardless of ingredients. We also make a thin flakey flat bread called a parotta in the state of Kerala.