How do you use each type of pressure can and which is best for beginners?

Bought a colour I like, not having a clue about pressures, and it says low pressure on the can...

Bought a black from a different brand as that brand had run out... but this brand can says high pressure..

How drastic are the differences and whats the easiest to get to grips with?

Whats their individual requirement; is it cap type? Distance? How much you push on the cap?

Keen to know more before I fuck up