I'd like to know:
- What's the difference?
- Which one needs akkusativ-object?
Same as buy in English. Works for pretty much every situation, from chewing gum to real estate to bribery ;)
Needs an accusative object, e.g.
This leans more towards shopping ("einkaufen gehen" = "to go shopping"). As a noun it is also often used in the context of a corporate purchasing department ("die Einkaufsabteilung", "Sie arbeitet im Einkauf.").
Can be used with an accusative object:
Note that "einkaufen" doesn't need an accusative object:
Another meaning of "einkaufen" can be to pay money to attain a certain status that is usually inherited or achieved through merit, e.g. to acquire an aristocratic title:
Similar to English usage ("to buy up something").
Needs accusative object in most cases:
Is also used in the context of company acquisitions. The company being bought is usually the subject and the passive form is being used:
Usually used in the sense of someone offering money for certain (used) items, e.g. (dental/jewelry) gold ("Goldankauf") or used cars ("Ankauf von Gebrauchtwagen").
Needs an accusative object: