Chamomile essential oil comes in two forms, Roman Chamomile and German Chamomile. I have included a picture of the German Chamomile essential oil to show the difference. The flowers of both plants look pretty similar, but the essential oils are quite distinct.

German Chamomile is a bluer color, and this is the one you want for things like calming inflamed, irritated skin. Not necessarily acne, but more itchy, flaky skin conditions such as eczema and psoriasis.

Roman Chamomile is the one you choose for irritable children, for colic, teething, for mild upset stomach. It is also good for irritated skin, and can be useful for acne as well as eczema. Roman Chamomile is a good choice for sun burn, and other inflamed types of skin conditions.

I tend to get the two confused, but I found that Ananda Apothecary does a good job of explaining the differences between the two. According to that site, both German and Roman are good choices for hair and skin care.

Roman is a more all purpose oil, whereas German has a very strong anti-inflammatory effect.

Interestingly, again according to Ananda Apothecary, the scent of German chamomile may have an effect of releasing old emotions.

Rub into the solar plexus or abdomen for best effect.

German Chamomile is a suitable oil for children.

Both Roman and German Chamomile are calming for the skin and digestive systems.