There's no need to be picky, mbps is a measurement of speed full stop.
But the main feature is people not getting the top speed.
Do these dim wit experts still not understand basic ADSL tech, so the "up to speed" is perfectly valid? :/
If you want to be picky, one is speed, one is a data rate more akin to flow volumes than speed or velocity.
Generally speed would be defined as time related to distance, megabits aren't units of distance, so can't really constitute a speed.
In technical parlance it is most definately not speed, its a rate, which is the number of things you want to measure happening in a given time, the confusion lies in that the descriptions are the same (ie fast and slow)