It's very bureaucratic. Beer and beer-based mixed drinks can be bought at the age of 16. Also wine and sparkling wine/champagne.
Alcopops are forbidden to people under 18 years. Also liqueurs are not allowed, with some exeptions: egg liqueur isn't allowed under the age of 18 (usually it has 12 - 20 ‰ but most of the egg liqueurs I know are between 12 and 14 ‰) but APEROL, which has 15‰ is allowed to teenagers of 16 years. Strange? YES!
Oh yes, like above mentioned: brandy, spirits and spiritous beverage are allowed at the age of 18.
But gambling (i.e. casino) or strip clubs are forbidden to people under 21 years.