Windboxes are hitboxes that deal knockback, but cause no hitstun. As a purely aesthetic conceit, windboxes will also make certain parts of a character, such as Link's cap, respond realistically to the wind. Windboxes are typically non-damaging, and are frequently push with too weak of a force to kill on their own. In competitive play, windboxes are typically used to gimp an opponent due to their ability to push opponents away from the ledge. That being said, if a player is hit with a non-damaging windbox by an opponent, and then promptly SDs, it will count as a KO for the opponent. In addition to not inflicting hitstun, windboxes cannot lift opponents off the ground, but can push them off edges.
Pushing refers to the windbox property being used by attacks, such as the Water Gun and F.L.U.D.D. to push opponents away from the attacker. Most push attacks work on both airborne and standing opponents, while characters hanging from a ledge are not affected. Since it is a form of knockback, its effect stacks with all other forms of movement (e.g fall speed or running), and cannot be directly opposed, instead decaying over time. As such, these moves can be very effective for keeping opponents away from an attacker or pushing them away from the stage.
From a physics standpoint, pushing is simply knockback without flinching. Because of this, it can KO characters and its overall effectiveness is affected by launch rates. Mr. Game & Watch's up air windbox with a launch rate of 2.0 will likely KO characters over the upper blast line. Additionally, since windbox velocity stacks with jumps, jumping while knockback from a windbox is active can cause the character to shoot upwards, potentially even leading to KOs off the upper blast zone which otherwise would not have occurred.
Pushing attacks that do not deal damage are ineffective against shielding opponents.
Sources of pushing include:
By enemies and stages
Conversely, pulling or vacuuming attacks (such as Inhale) cause characters, as well as certain items, to be gently pulled toward the attacker. Contrary to common belief, these are identical in property to pushing attacks, but simply have an angle that pulls opponents inwards instead of pushing them outwards.
Sources of pulling include:
By enemies and bosses
Items affected by both pushing and pulling