I have not timed the charging times, but when charging my tablets I think that a power bank such as this http://www.gearbest.com/chargers/pp_171371.html charges much faster that the wall chargers. Is that my imagination?
Thanks,
Jerry
Unlikely. Your device cotrols the max charging current, and that’s typically achieved on an oem wall charger.
Hey jerm03.
We now have so many different charging protocols out there, that I would need a great deal more information from you, to even begin to help you.
We’ve heard of quick charging, turbo charging, adaptive fast charging, rapid charging, and Qualcomm Quick Charge 1.0, to 2.0, to the latest Quick Charge 4+ > http://bit.ly/2sFxMNV
Some cables are only capable of a certain current amount. Does your tablet have micro-USB, or USB type C? Some power banks have a 1.0A port, some have a 2.0A port. Some have both! 
Some will charge two devices at once, but then often cut the amp rating to each port during the charging process, if charging two at once. Are you planning on charging two devices at a time?
You didn’t mention your tablets make or model? You didn’t say what your wall charger output is rated at? You also didn’t mention if those two came together in the same package? Made for each other, or if you later bought a third party option, to use as the wall charger?
I calculate at least 13.8 million possible combinations of answers to give you. So . . . you’ll have to be a bit more forthcoming with your information 
As with anything, it is possible.
Properly speaking, it is not the constant voltage power supply who makes the stuff charge faster, but the device (tablet, smartphone, etc) which, depending on the data lines configuration/negotiation and the perceived voltage drop over its internal power management circuitry, determines how much current it can make use of. Thence, upon plugging if the power supply id is 0K the device will try to pull all of the current it is set to (hardware and ROM based), but of course if this results in too much voltage drop it will throttle back until the input voltage is sufficient. Lots of things can make this go bad: weak supply, weak cable, dirty/damaged plug contacts, etc.
Recently I opened up my smartphone to “tighten” its micro USB female, and after a bit of fiddling and cleaning it the male plugs now insert tight and, to my surprise, current flow has improved a bit (I wasn't really expecting that).
Thanks, guys. I figured I would get in “over my head” pretty quickly. I am unable to answer any of the questions, except I am charging Amazon Kindle fire tablets.
Thanks for the comments.
Jerry