To my knowledge, no one uses p/us in expediting. Local courier companies might.
Don't just jump into expediting. Look in the classifieds here to see who is looking for a driver. Drive for them a while, just to get the feel of it. Can you handle sitting for 3-4 days between loads? It can get pretty boring out there.
Do you have a CDL with haz-mat (hazardous materials) endorsement? Many of the expediting companies require it, even for van drivers (although I don't know that *all* companies do).
Another thought: Neither will bring much, if any, profit.
Hope this helps.
Stay safe out there!