I fail to see how you came to such a distinction. I'd say it's closer to one being mysql and the other one being mariadb, it's not like any of them focuses on correctness or anything.
based on the link below https://gist.github.com/chriseppstein/674726 Sass appears to be more verbose in accomplishing the same goal... so... I think Less is more like CoffeeScript and Sass is more like Javascript?