power bank VS battery

A power bank is a battery, so what you mean exactly? Better for what? What device?

for smartphone

power bank i mean the portable power pack and can storage power and then charge for cellphones,and bettery i mean that just attach in our cellphone and must use charger to gain more energy,and can not last too long.At the same time ,the PRICE is also different,and so i want ask how to measure this matter.Can you give me some suggestions,just a discussion,and which will be more popular in the futher?

Is this some kind of ask/response spam? The question seems misconceived. An internal battery is necessary in a portable device; an external battery in a case (a "power bank") is useful but not necessary. Not all devices use power banks the same way. I have 2 devices: 1. An Android mobile phone. If you plug the phone into the power bank, it will recharge the battery and at the same time you can use the phone normally. 2. A Nikon Coolpix portable camera. If you plug this into the power bank, it simply recharges the battery, you cannot use the camera during this time.