The main differences between a Jack plane and a block plane are, to start off with, Jack planes are longer in length than a block plane, block planes tend to be compact and can be used with one hand if required.
Jack planes are, (and some might argue, are not) a specialist woodworking tool, known as a very versatile hand woodworking tool, they are often used for removing warps and twists in wood or smoothing out rough surfaces and help to true up long lengths of timber.
Block planes really are the type of plane that you see around the most, most DIY enthusiasts will own a block plane because of it’s generally cheap purchase price and compact size.
Block planes are designed for cutting end grain, chamfering and shaping pieces of wood and are a great all rounder hand plane to have in your collection.