SE, it is time to speak up

[Niwashi]

You can do both. However you can't do cross breeding like you can with a garden. You can decorate but have a lower amount of items you can place (100 for apartment and 200 for small house). You also can't add more people to your apartment like you can with a house.

Plus the limitation that decorating can use indoor items only. There's no place to put (or even store) something like a tree that you'd gotten in an earlier seasonal event.

Also there's no workshop in an apartment.

Well, there's no workshop in a personal house either. This limitation really comes down to the fact that apartments are limited to being personal only. There's no such thing as an FC apartment.