From the ECB:
The new €5 banknote has benefited from advances in banknote technology since the first series was introduced over 10 years ago. It includes some new and enhanced security features. The watermark and hologram display a portrait of Europa, a figure from Greek mythology – and hence the name of this series of banknotes. An eye-catching “emerald number” changes colour from emerald green to deep blue and displays an effect of the light that moves up and down. Short raised lines on the left and right edges of the banknote make it easier to identify the banknote, especially for visually impaired people.
Compare it to the old one:
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