Do not pretend it is different - the alcohol is one of the integral part of meeting people and therefore vital part of Erasmus+ experience. Everybody knows that, so why not tell you more about what so different about culture of drinking in Sweden.
The legal age for drinking in bars in Sweden is 18 (let say this is more or less normal), but you will find that some nightclubs and pubs in Stockholm have a different policy in terms of age restrictions. And the policy also concerns cost of entrance. One night we spend almost 3 hours looking for a club because one we found before had free entrance but as it turned out only for girls (that would be it when comes to gender equality :D). And few others were allowing only people at least 21 years old (French people were 20). So, clubbing in Sweden demands lot of planning - good tip is to check everything carefully regarding age, cost and hours.
Secondly, you can ONLY buy stronger alcohol (more than 3.5%) in the public liquor store called: Systembolaget. They can be found all over Stockholm. The legal age for buying alcohol is 20, (even though you can drink when you are 18) so always bring your ID with you! Opening hours are normally Monday to Friday: 10-19, and on Saturdays: 10-15. After that hour there is no way to buy alcohol except for the pub. And we learned it hard way when we failed in buying wine for ours friend birthday, so bear that in mind and plan your shopping.
The stronger alcohol is ridiculously expensive. The most economical beverage is wine (you can buy 3 liter box for around 100--120 SEK). But you do not want to see the price of the stronger liquor. People usually take it with them from abroad (BTW it is another reason to go for a Sea Battle or any other trip as well as for inviting friends over).
The average price for a beer in Stockholm is between 40-80 SEK. The cheapest places to drink (except student pub) are located on Sodermalm. Here I am giving you the list of few before you will discover your own ones:
Hellströms Bar and Restaurant: beer - 29 SEK. Adress: fatbursgatan 1.
Carmen bar: It's nothing special, but good for students. Offers not only drinks but also food. Adress: 14 Tjaerhovsgatan
Pub Kloster: beer around 30 SEK, nice atmosphere but really crowd on weekends. Adress: Hornsgatan 84
Curiosity: in Sweden the most crazy parties are on the weekend after payment. Yes, you understood correctly everyone gets paid on exactly the same date and that the time when whole Stockholm is one big party and the only time of the month when you can see drunk people with Viking horns. But if you do not like overcrowded places do not get out on this dates.