Charge rate would be a difference between the 2. Take for example a 3000mah pack: if the pack is 3C capable - you would be able to do 9.0A with charger #1. Charger #2 would only be capable of 2C as the max is 6.0A.
I personally only charge my packs @ 1C which equates to 5.0A (my biggest capacity pack is 5000mah)