在美国版知乎Quora上面，有人专门针对portable charger进行了解释↓↓

A portable charger, better known as a “Power Bank” is a device that has a sole purpose of being a power supply for devices like smartphones or a tablets. Power banks have large batteries within them that are able to hold quite a large capacity.

翻译：

便携式充电宝（portable charger），更广为人知的名称是“Power Bank”，它的唯一目的是为智能手机或平板电脑等设备供电。移动电源内部装有大电池，可以容纳相当大的容量。

我还找到一个叫做www.powerbankexpert.com（充电宝专家）的网站，上面阐释了power bank和portable charger到底有区别没有↓↓

Power Bank or Portable Charger? Which one is the correct term?

A question we see a lot is – what is the difference between a power bank and a portable charger? To put it simply both terms refer to the same class of devices and can generally be used interchangeably.

翻译：

Power Bank还是Portable Charger？那个术语是正确的？

我们经常看到的一个问题是——a power bank和a portable charger有什么区别？简单地说，这两个术语都指同一类设备，通常可以互换使用。