Cotton is a fiber (from the cotton plant). Flannel is a finish or weave. Hence you can have flannel wool as well as cotton flannel - i.e wool made with flannel finish or cotton made with flannel finish. Hope this helops.
A very memorable song from Joni Mitchell that featured the line They paved paradise and put up a parking lot.. This best described places I remember growing up in Bloomington, MN in my teens where numerous places were torn down, most notably a restaurant I frequented that was replaced with a Park and Ride lot.
_____ As originally written, the song, Somewhere Over the Rainbow, had a prelude: When all the world is a hopeless jumble And the raindrops tumble all around, Heaven opens a magic lane When all the clouds darken up the skyway, There's a rainbow highway to be found Leading from your window pane To a place behind the sun, Just a step beyond the rain The prelude makes the song even more poignant.