Switchblade vs. Assisted Opening Knives
Spring assisted knives and switchblades are both types of folding knives that use springs to help with opening the blade, but they differ in their mechanism of action and legal status.
How an Assisted Opening Knife Works
A spring-assisted knife has a mechanism that allows the blade to be partially opened with a flick of the wrist. Once the blade is partially opened, a spring takes over and helps to fully open the blade. The user must still manually open the blade to some extent, but the spring provides additional force to make the process easier and faster.
How a Switchblade Works
A switchblade, on the other hand, has a button or lever that triggers a spring-loaded mechanism to release the blade, which then snaps into place with the help of the spring. Switchblades are often also known as automatic knives or push-button knives.
In terms of legal status, switchblades are typically more heavily regulated or even banned in many countries and US states due to their association with criminal activity. Spring-assisted knives, however, are generally legal and can be carried in most places as long as the blade length is within legal limits.
How to Tell the Difference
The best indicator to tell if a pocket knife is a switch blade or assisted opening is what the resting position of the blade is. If the blade opens without any resistance (button or switch), it's a switchblade. If there is nothing blocking the blade and it stays closed, the knife is an assisted opener (assuming it has a mechanism to help open the knife).
Another way to look at it: If you are able to open the blade without exerting any effort on the actual blade, it's a switchblade. Conversely, engaging an assisted opening knife requires you to put some pressure on the actual blade, whether on the thumb stud or a rear lever connected to the blade, before the opening mechanism takes effect.
Finally, the last surefire way to tell if it's a switchblade is if it has a button that engages the knife. No assisted opening knife will have one.