Lower belt patterns have more fist movements and long range techniques. Higher belt patterns have more open hand movements and close range techniques.
Not all movements are intended for actual application, some are only included to condition the muscles and reflexes. So possible application of pattern movements are open to interpretation. Higher patterns emphasize hand techniques not introduced in the color belt patterns. Therefore, if you do not progress beyond black belt, you miss out on many hand techniques. This means that taekwondo usually does not get credit for many of its hand techniques. Movements in the patterns emphasize the action-reaction principle. They teach how to chamber before movement which helps set the rhythm of the pattern. Each movement sets up the next movement by using a action/reaction movement and the momentum resulting from it. Thus, the thrust of one movement leads into the next movement so transitions are smooth.
Patterns stress hip snap and torso twisting for power generation. It is not always clear as to whether a technique is an offensive or defensive technique. Sometimes they may be both. Sometimes blocks target pressure points for immobilization. Higher forms have the chi-component. Energy is directed into a hard block with a tensed fist. Instead, open hand blocks let energy flow using the "water principle." Knife hand blocks are not used in a stiff stopping motion but are used in a deflecting push-through motion. Lower rank patterns use blocks that block an attack at the end of its motion. Upper level blocks block and attack before its movement is completed. sometimes targeting a pressure/nerve point. Some techniques in patterns are feints that set the opponent up for a following technique. Some movements are performed in rapid combination.
Most ITF patterns start to the left first because most people are right handed. They block with the left arm and attack with the right. Since emphasis of taekwondo is on defense, most patterns start their movement to the left. There are exceptions such as in qwang-gae.