Austrian grenadiers were organized into battalions, not regiments. In 1805, each regiment had a grenadier battalion, and it carried the white Leibfahne, as it was the most prestigious in the regiment. In 1809, each regiment of line infantry had two companies of grenadiers in its grenadier division. In wartime, grenadier divisions from three regiments would be combined into a grenadier battalion, which would be referred to by the name of its commander. In battle, they carried an Ordinarfahne from one of the three regiments, usually the senior-most regiment.

For future reference, this would be a good candidate for the Short Answers to Simple Questions thread.