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.

They’re the same thing

You should probably use dough. Your hand would get severely burnt. /s

Because butter tastes amazing, not everyone likes using lard, or pork products in general.

My excuse is lard and vegetable shortening is hard to get here. My reason is butter is great.

A vegetarian option?

I think it’s pretty common to make flour tortillas with some incorporated fat, unlike corn tortillas.

I don’t know what Bordier butter is, but my wife and I get really fancy Irish or Amish butter, and I have recently had to start insisting that we keep some regular non-premium butter around for just this reason. It feels wasteful to grease a pan with super-fancy premium butter, or to use it in certain recipes.

They sell cook’s butter (called «Brut de Baratte») which is about half the price and really nice to work with.