I thought I mentioned the source for this. It is Bressonnet. I have posted it before anyway but you'll find it below.
It isn't a case of what I believe, it is a case of this is the only specific description I have ever seen of a grand bande and the way it was different is that a grande bande was a 'corps principale' whilst tirailleurs de combat only operated in support of and subordinate to their parent battalion.
I have never seen a remark to the effect that combined voltigeur battalions were a grande bande specifically but in 1806 anyway it is clear that such elite battalions were formed from voltigeur companies, and grenadier companies, and employed as part of formation advance guards.
Those armies that didn't have dedicated light companies in their battalions, and I am thinking of the Prussians in particular, used, I think, the senior captain of the battalion to command the skirmish platoon.
Anyway, Bressonet's 'Etudes Tactiques sur la Campagne de 1806' pp369-371 quoting Colonel M Marbot whose 'Remarques Critiques sur l'ouvrage de M le Lieutenant General Rogniat intutile Considerations sur l'Art de la Guerre', earned him 100,000 francs in Napoleon's will.
Neither Bressonet nor Marbot tell us how tirailleurs en grande bande were controlled, but it does say that they were the exception rather than the rule and that tirailleur de marche et de combat were the norm. If you consider that each brigade could deploy something like up to four or five voltigeur companies as tirailleurs de combat, it is easy to see how observers might report 'swarms' of skirmishers which then becomes intepreted as a grande bande when it is nothing of the sort.
Anyway, here is my translation of the passage.
"Colonel Marbot divides the skirmishers (tirailleurs) into two very distinct categories: tirailleurs de marche et de combat, and tirailleurs en grande bande. The first act in concert with their battalion for which they scout on the march and cover during battle. They have their origin
in the pickets that battalions used to detach for their security.
These skirmishers, says Marbot, are used to repulse the first posts of the enemy, and to probe, so to speak, his position.
But their main goal is to carry disorder to the hostile line. They devastate the enemy, who is forced to move his masses away and withdraw his skirmishers. The object is to throw back the enemy skirmishers onto his attacking troops and to carry disorder to its columns.
That is how the skirmishers of the two parties, wanting to protect their own line and inconvenience that of the enemy, mutually neutralize each other and do not decide anything because it is the shock of the masses on which the combat depends and as soon as they join, the skirmishers become useless, an embarrasment, and it is necessary that they join the line.
The tirailleurs de marche et de combat are, therefore, subordinate to the action of the battalions, for which they prepare the attack, scout and between which they rally. Their action alone can never result in a decision.
The tiralleurs en grande bande, on the contrary, form a main body the object of which is to storm or defend a position, or to turn the flank of the enemy.
In the War of the Revolution, in the face of positions reinforced by fortifications and occupied by good troops on which a frontal attack could not avoid resulting in heavy losses, several French generals used tirailleurs en grande bande in the same way for attacks, and always with success.
These generals believed that there were no positions that one could not turn, no steep mountains that one could not climb, and knowing that scattered men can easily penetrate into the centre of any obstacle, which would be impratical for troops in column or in line to do, they loosed on one or two flanks of the position that they wanted to storm, a battalion, a regiment and sometimes even a complete brigade as skirmishers, while another, formed in column, out of the reach of artillery, threatened the front of the entrenchments.
The tirailleurs en grande bande were, therefore, a good main body, that is to say one sufficient of itself, which could lead an action until the very end, take charge of fighting in terrain that could not be done by units in close order. It was the extension of this principle which brought the creation of the light troops, and it is worth noting that the actions of tirailleurs en grande bande was a speciality reserved for these troops during the Wars of the Revolution. However, if the case arose, line infantry, as well as light demi-brigades, were also used in this role.
However, tirailleurs en grande bande were the exception on the fields of battle and, on plateaux of the Saale, in the combats of 1806, neither the circumstances nor the terrain required their use. One notes the use of tirailleurs en grande bandes once, on the evening of the battle of Auerstedt, for the attack the steep position of Eckartsberga, when the 1er battalion of 48e was detached entirely as skirmishers on the left of the Prussian line.
With that exception, there were no tirailleurs en grande bandes, of any kind. On the other hand, it emerges from the detailed survey of the battles of October 1806 that the use of tirailleurs de marche et de combat was constant to some degree or another."