That's correct - the monogram speedy is the original. Mini lin is a new line.
Personally, I love the monogram. To me, the mini-lin looks like a grandma bag (LOL!). My SA told me that they have had a lot of complaints on the mini lin, both with pilling/snagging, but also that on the fabric bags if you spill something colored on them, it can be impossible to clean. On monogram speedies - baby wipes.
I really love my mono speedy (like my Damier Speedy too). The mini lin to me is classic, but kind of boring. If you like the dark brown, how about damier? Same colors, a little more "punch" and nicer quality.