Both matcha and regular green tea are made from Camellia sinensis plant. The biggest difference lies in the processing of the leaves. Ceremonial grade matcha contains only pure leaf material, de-veined and de-stalked, and powdered using stone mills right before packaging.
All regular green tea needs to be steeped in hot water to release flavor and nutrients. Green tea can be made from hundreds of different tea cultivars, but not all of them can be used for making matcha. Matcha tea plants require shading to develop specific flavor and color, a step not commonly used in production of other green teas.
Although all green teas contain caffeine and EGCg, in some tea types those levels can be very low, especially in teas that are roasted, more processed, made from mature leaves and harvested in autumn. Ceremonial grade matcha is harvested in spring, using fresh spring leaves and buds, and unroasted.
Some green teas might have more EGCg than matcha, but it is impossible to extract the whole content with regular brewing. That’s what makes matcha the healthiest tea in the world – powdered form allows you to ingest the whole leaf. Leaves can, however, contain not only good compounds, but different chemicals, fertilizers and toxic substances as well. They all will also be ingested by drinking matcha, so choosing organic is important, especially with tea powders.