Kaufen vs. erwerben
The German words kaufen and erwerben both translate to to buy or to purchase. However, they are used in different contexts, with the main difference lying in their level of formality and the nature of the acquisition.
Kaufen
A1Kaufen is the most common and neutral word for to buy. It is used in everyday language for all kinds of daily shopping and transactions.
Ich gehe heute Nachmittag ein neues Buch kaufen.
(I am going to buy a new book this afternoon.)
Hast du die Milch gekauft, die ich auf die Liste geschrieben habe?
(Did you buy the milk I wrote on the list?)
Wir wollen uns nächstes Jahr ein neues Auto kaufen.
(We want to buy a new car next year.)
Sie hat sich eine teure Handtasche gekauft.
(She bought herself an expensive handbag.)
Man kann die Tickets direkt am Eingang kaufen.
(You can buy the tickets directly at the entrance.)
Erwerben
B1Erwerben is a more formal and elevated term for to acquire or to purchase. It is often used for items of significant value (like property or companies), or for things that require effort to obtain, such as skills, knowledge, or a reputation.
Das Museum konnte ein seltenes Gemälde von einem privaten Sammler erwerben.
(The museum was able to acquire a rare painting from a private collector.)
Er hat seinen Hochschulabschluss an einer renommierten Universität erworben.
(He earned his university degree from a renowned university.)
Der Konzern plant, weitere Anteile an dem kleineren Unternehmen zu erwerben.
(The corporation plans to acquire more shares in the smaller company.)
In diesem Kurs können Sie wichtige berufliche Fähigkeiten erwerben.
(In this course, you can acquire important professional skills.)
Durch seine Zuverlässigkeit hat er sich das Vertrauen seiner Kunden erworben.
(Through his reliability, he has earned the trust of his customers.)
Für den Erwerb dieser Immobilie ist ein erhebliches Kapital notwendig.
(Significant capital is necessary for the purchase of this property.)
Summary
In essence, use kaufen for your everyday shopping and standard purchases like groceries, clothes, or a car. Use the more formal erwerben when talking about significant acquisitions like real estate, companies, and valuable assets, or when referring to the acquisition of non-material things like skills, degrees, knowledge, or a reputation.