A pocket knife is a folding knife with a blade that fits into the handle and is small enough to fit in a pocket. Most modern pocket knives are designed for light loads – and are a useful tool for very small tasks you can perform when the knife is uncomfortable. There are some companies like Cherrycutlery that provide the best pocket knife online.
Pocket knives have blades that are held in place by a spring mechanism, open or closed pocket knives with single or dual blades are available, some have attachments and even forks and spoons – many options depending on the intended use disadvantage of this type of pocket knife – because the knife is not opened, the knife can be closed accidentally.
Jackknifes, on the other hand, are usually slightly larger, stronger, and have some sort of locking mechanism to keep the blades open. Due to this added strength, they can cope with more difficult tasks.
But because they are larger, they are usually carried in a bag rather than a bag. This locking mechanism makes the folding knife a bit more secure as the lock prevents the knife from closing accidentally. These knives come in many designs and usually only have one blade.
So before you buy a knife, you should check local knife carry laws. Most pocket knives are legal to carry (except in places like courthouses, schools, etc). Whether a knife is "legal" to carry is usually determined by blade length – from my limited research, knives with blades of less than 3 ½ – 4 inches are usually legal – but do check your local laws.