[shorod]

Yes, jumper cables are much more likely to spark. Most modern jump start pack either have switches or relays so there is no or very little power available to the clamps when connecting them. Once the clamps are connected, either a switch is triggered or the "smart" clamps sense a correct voltage and polarity and close a relay. With no spark, the risk of having an issue if a battery is leaking some of the gas is greatly reduced.

Although having never experienced an issue from modern car batteries leaking gas, I'm probably a bit more willing to go straight to the battery terminals with jumper cables than someone who has experienced a leaking battery.

-Rod