Tortillas have fat (lard or vegetable shortening) and leavening (baking powder) typically, and from what I recall roti have neither.

I am not an expert on either, but I did grow up and live in NM where our tortilla sections are larger than our bread sections in the grocery stores.

Texture and taste are different. Flour tortillas are somewhat airy due to a leavening process and they also tend to have a very mild sweetness.