How to recognize Artemisia Annua from Artemisia Vulgaris?

 Artemisia Annua (Annual Mugwort)

The plant has highly branched stems. The leaves are very divided.
It is an asteraceous, so the flowers are actually flower heads. They are small, say 1-2 mm in diameter, yellow in colour and are located in clusters.
Artemisia annua is a herbaceous plant with a single upright pyramid-shaped stem. If crushed, its stump can produce one or two more stems. It is a highly branched, hairless plant, usually 50-150 cm high, but can reach 200 cm.

 Artemisia Vulgaris (Common mugwort)

Its foliage is dark green on the upper side and whitish tomentose, covered with a downy coat of fine hairs on the underside, its downy flower heads are tightly packed and very abundant on the branches.
Smells like vermouth or tea

 What is the difference between Artemisia annua and Artemisia vulgaris?

The smell is very different. Artemisia vulgaris is aromatic, but very sweet, whereas Artemisia Annua is very strongly aromatic and spicy.
From my experience as a grower, the only thing you can tell about Artemisia Annua is the bitterness. Artemisia Annua is inherently very bitter.
Therefore, we often recommend adding a little honey and lemon to Artemisia Annua tea.