arrangieren
to arrange
To organize, plan, and prepare something, for example an event, a meeting, or a trip.
Wir müssen schnell ein Treffen mit dem Kunden arrangieren.
We need to quickly arrange a meeting with the customer.

to arrange
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to arrange
To organize, plan, and prepare something, for example an event, a meeting, or a trip.
Wir müssen schnell ein Treffen mit dem Kunden arrangieren.
We need to quickly arrange a meeting with the customer.

The meaning depends on the object: With abstract things like 'Treffen' (meeting) or 'Reise' (trip), it means 'to organize'. With concrete things like 'Blumen' (flowers) or 'Möbel' (furniture), it means 'to arrange'. With 'sich' and 'mit', it means 'to adapt' or 'to come to terms with'.
Sie hat ein Interview mit dem Manager arrangiert.
She arranged an interview with the manager.
In the meaning 'organisieren' (to organize), the word is often used for social or business occasions: 'ein Treffen arrangieren' (to arrange a meeting), 'eine Feier arrangieren' (to arrange a celebration), or 'eine Überraschung arrangieren' (to arrange a surprise).
Könntest du für nächste Woche einen Termin arrangieren?
Could you arrange an appointment for next week?
This meaning often refers to a creative or decorative arrangement. Typical objects are 'Blumen' (flowers), 'Möbel' (furniture), 'Fotos' (photos), or 'Waren' (goods) in a shop.
Die Künstlerin arrangiert ihre Skulpturen im Raum.
The artist arranges her sculptures in the room.
The meaning 'sich anpassen' (to adapt) always requires the reflexive form and the preposition 'mit' (with). The structure is: sich mit etwas (dative) arrangieren.
Nach einiger Zeit hat sie sich mit dem Gedanken arrangiert, umzuziehen.
After some time, she came to terms with the idea of moving.
to plan
'planen' and 'arrangieren' can both mean that you prepare and organize something. 'planen' is the normal word when you think through what should happen, when, and how. 'arrangieren' puts more emphasis on making concrete things possible, for example an appointment, a meeting, or a trip. It often sounds a little more elevated or formal than 'planen'. So you can plan a party, and then arrange the rooms, appointments, or help.

Morgen arrangieren wir ein Treffen mit der neuen Kundin.
Tomorrow we are arranging a meeting with the new client.
Für den Sommer planen wir eine Reise an die Ostsee.
We are planning a trip to the Baltic Sea for the summer.