Oolong vs Green Tea: Processing, Taste, Caffeine and Brewing Compared

Oolong and green tea come from the same plant, Camellia sinensis. The difference is processing. Green tea is heated right after picking, so it barely oxidizes and stays fresh, grassy and nutty. Oolong is tossed, bruised and left to partly oxidize before heating, and is often roasted afterwards, so it tastes more floral, creamy, fruity or toasty. Oolong is brewed hotter, with more leaf, and lasts many more steeps. Caffeine is similar and depends more on the specific tea than on the category.

For my first couple of years with Chinese tea, I honestly thought a light, green-looking Tieguanyin was a kind of green tea. It was green, after all. Then I brewed it next to a Longjing and the difference was obvious in the first sip: one tasted like toasted beans and spring grass, the other like lilac and fresh cream. Same plant, completely different drinks. Here's why.

The short answer in a table#

How they're made: where the difference starts#

Every tea is basically a question of when you stop oxidation.

Green tea is heated almost immediately after picking, usually in a hot wok or drum in China. This "kills" the enzymes that would turn the leaf red, so the leaf stays green. Then it's shaped and dried. Nothing in the process softens its bitter compounds, which is why green tea is so easy to over-brew.

Oolong takes a long detour first. The leaves are withered, then tossed and rested again and again over many hours. Tossing bruises the edges, which oxidize faster than the centre, giving the classic "green leaf with a red rim". Only then is the leaf heated to stop oxidation. After rolling and drying, many oolongs are also roasted, sometimes for a whole day over charcoal.

That long, careful "managed stress" of the leaf is what turns grassy notes into flowers and fruit.

How to tell them apart#

The light, green-looking oolongs are the ones that confuse people. Three quick tests:

• Look at the wet leaf. Oolong leaves are always bruised and often show reddish edges. Green tea leaves are evenly green.
• Smell it. Light oolong smells floral (lilac, orchid). Green tea smells grassy, nutty or bean-like.
• Taste it. Oolong is creamier and smoother; green tea is fresher, more vegetal and more likely to turn bitter.

Taste: what to expect#

Green tea is about freshness: spring grass, toasted beans, chestnut, sometimes orchid. It's light and bright, with a clean sweet finish when brewed well.

Oolong covers a huge range. Light oolongs are floral and creamy. Roasted oolongs taste of toast, caramel, dark fruit and minerals. In between you'll find honey and peach. The full flavour map is in what does oolong taste like.

Caffeine: which has more?#

Neither, reliably. Both usually land in the same range, roughly 12–43 mg per 100 ml. Bud-heavy green teas can be quite strong; oolong is usually made from more mature leaves, but it's brewed with more leaf and hotter water. The tea and the brewing matter more than the category. More in caffeine in tea.

Brewing: side by side#

In a mug: green tea 1.5–2 minutes at most at 80 °C; oolong 2–3 minutes in hotter water (80–95 °C, depending on the roast), and you can re-steep it two or three times. Full numbers in my gongfu brewing chart.

Storage#

• Green tea is the most fragile tea there is. Light, heat, moisture and odours dull it quickly. Keep it airtight, dark and cool, and drink it within about a year of harvest.
• Light oolongs also lose their fresh floral notes: about a year is a good guide.
• Roasted oolongs are much more stable and can keep and even improve for years.

More in how to store tea.

My side-by-side#

Spring Longjing vs a light Anxi Tieguanyin, each in a 100 ml gaiwan, brewed to its own best parameters.

The Longjing was over after five steeps. The Tieguanyin was still going at eight.

Which should you choose?#

Choose green tea if: you love fresh, grassy, nutty flavours, you drink tea in spring and summer, and you don't mind being careful with water temperature.

Choose oolong if: you want more aroma and body, a forgiving tea that's hard to make bitter, and a session that lasts a whole afternoon.

Can't decide? Start with a light Tieguanyin: it's the bridge between the two.

Myths#

"Oolong is a mix of green and black tea." It isn't a blend. It's a separate way of making tea with its own steps.

"Green-looking oolong is basically green tea." The rolled leaf, the bruised edges and the floral taste say otherwise.

"Green tea is always lower in caffeine." The ranges overlap.

My honest take#

If green tea keeps turning bitter on you, try an oolong before you give up on Chinese tea. It's more forgiving, lasts longer in the pot and in the cupboard, and gives you far more to explore. But don't skip green tea entirely: a fresh spring Longjing brewed properly is one of the great pleasures of the tea year.

The bottom line#

Green tea and oolong are the same plant made two ways: green tea is unoxidized, fresh and grassy; oolong is partly oxidized, often roasted, and floral, creamy or toasty. Oolong takes hotter water and gives more steeps; caffeine is similar. Explore both in my guides to Chinese green tea and Chinese oolong.