No, they're completely different things. They do not function the same way. As rwl replied, a "trigger crank" is a device that is inserted into the trigger guard, rotates, and repeatedly activates the trigger. Such a device is very likely ILLEGAL.

The ATF recently issued a letter regarding the "Auto Glove" - an electrically-powered device worn on the hand which presses the trigger at variable rates. The ATF said the glove was a "machinegun". http://14544-presscdn-0-64.pagely.netdna-cdn.com/wp-content/uploads/2017/09/atf-autoglove-determination-9-11-2017-redacted.pdf

Bump-firing uses the firearm's recoil to move the entire firearm, while the finger that presses the trigger remains stationary (with respect to the moving firearm). The result is that the shooter's finger is repeatedly pressing the trigger.

Bump-firing requires no special stock. Before such stocks, people used rubber bands and belt loops. Or just their hands.