Simple Combat Rounds
Each combat round is about 5 seconds. Characters can perform one action or they can perform multiple actions by splitting their die pools per normal. Every movement, every attack, and every parry must be part of an action.
Cinematic Combat Rounds
Each combat round is about 30 seconds. Some light movement, feints, and the like are "free" and assumed while all combatants try to position themselves for the best attack.
Characters perform two actions every round. The first action represents an attack or casting a spell. This action can be split into multiple actions, usually for attack multiple foes. This is referred to as the "A Action"
The second action represents a defensive action such a parry, a movement action such as a charge or leap, or a social action such as a taunt or intimidation attempt. This is referred to as the "B Action."
Characters can choose to swap their "A action" for a second "B action." If a player uses both actions to parry or dodge, the two rolls successes are added together. A botch on either roll brings the total to zero.
Play testing so far indicates that Cinematic play testing generally makes more interesting fights, less tedious fights, while Simple Combat Rounds generally makes for more realistic fights.
Usually, PCs and NPCs use their A-action to attack with a weapon or a spell and their B-action for a dodge or parry, but it opens options. For instances, an archer will often use part of the B-action to reload and then make a dodge with a multi-action penalty, so he can keep shooting with his full attack roll. I had one player who was fond of having her half arc incorporate parkeur maneuvers into attacks and this is easier to allow with cinematic combat rounds than simple combat rounds.
On the whole, Cinematic actions are the "default" unless the Game Master says otherwise or the players unanimously ask for simple combat rounds.