Living Arrangements - refers to the way someone organizes how and where they will live or how many people live with them. It can also describe if rent has to be paid.
For example: If you are sharing an apartment with a friend, you can arrange to pay half of the rent. You can also arrange who gets which bedroom.
Living Conditions - refers to the state of the dwelling. This means you can have good conditions or bad conditions.
For example: If your apartment has water, electricity, phone, clean floors, kitchen, bathroom, ect then you have good living conditions.
If your apartment has rats, no access to running water or if the ceiling is falling apart, then you have bad living conditions.
I hope this was helpful to you.