Rationale: I am making flashcards and I need to give myself tips to differentiate between similar words. Sometimes (actually in German very often) there are couples of transitive verbs that share the (almost) same meaning with the following grammatical difference:
(1.) in one the Akkusativ Objekt is compulsory;
(2.) in the other, the Akkusativ Objekt is an extra-information.
A basic example is kaufen and einkaufen. This is not the most illustrating instance as the meanings ARE different. Yet, I want to focus on the Grammar (if you are not happy with kaufen/einkaufen, think of begießen/gießen).
"kaufen" needs always an Akkusativ Objekt. The sentence "Ich kaufe" by itself is incomplete. Yet, one can say "Ich kaufe ein". This one can gramatically survive.
To reiterate my question: is there a proper name for the two categories of transitive verbs like kaufen and einkaufen?