Moving from one apartment to another can be stressful when there is a time element involved – someone’s taking your old apartment on the first of the month, but you can’t move into your new place until the first!
For those moving from a house to an apartment, there’s the issue of “stuff” – most likely, you will have more of it than can reasonably fit in your new apartment, so the decision becomes about selling, storing or cramming it all in there.