No you cannot use it without comparing. The one meant for your phone may not have enough mA output. Check the AC to USB that came with your
ecig and see what volts and what amps it puts out. Anything between what your
ecig's AC to USB puts out and standard USB which is 5v 500ma (.5A) will be OK (and in fact the mA output of the car USB can even be higher (I have one that is 2A aka 2000mA) - the battery cable will only take what mA it needs). Any adapter that puts out less voltage or less mA than what your ecig AC to USB puts out, or puts out more voltage than 5v will not be usable.
Chances are your adapter will be usable for charging a battery but you have to check them. However, if the car charger did not come with your phone and was purchased separately as a standard car lighter to USB, then it is probably 5v and 500mA and that would be fine (USB spec, same as a motherboard USB slot on a PC)