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[Veqq]

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[corcaighist]

Good luck with the Finnish learning and the wedding! I myself just started learning Finnish a few days ago and am finding it enojoyable though I do have an advantage having been exposed to Estonian the last few years. I am also getting married this summer to an Estonian whose family doesn't speak much English, at least not the middle and older members. I've started on Finnish in case we decide to move to Finland in the near future. I'd like to be able to get around and not have to fall back too much on English or Estonian.

[Veqq]

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[corcaighist]

Thank you! I wish you lots of luck with that as well

hotellilla/hotellissa on (stuff) <- I was told that they're basically interchangeable to indicate possession and that it's with buildings specifically where you can do this. ...why?

Be careful of asking native speakers for grammar advice. They will be able to give you examples of correct usage but not be able to tell you why.

Hotellissa on uima-allas.
The hotel has a pool. / There is a pool in the hotel.

This sentence could be either read as one of possession (hotel has a pool) or one of location (a pool is at hotel). To say that the pool is in/at the hotel we say:

Uima-allas on hotellissa.

In Finnish, when both possessor and possessee are concrete and inanimate we make use of the INE case in place of the ADE. This distinction does not exist in Estonian and we stay with the use of the ADE case.

Compare:

Mix of concrete/abstract and animate/inanimate.

F: Pojalla on kiva nimi. (ADE case)
E: Poisil on kena nimi.
The boy has a nice name.

F: Mulla ei ole rahaa. (ADE case)
E: Mul pole raha.
I don't have any money.

and

Both concrete and both inanimate:

F: Tässä ruuassa ei ole makua. (INE case)
E: Sel toidul ei ole maitset.
This food has no taste.

F: Tässä pöydässä on vain kolme jalkaa. (INE case)
E: Sel laual on ainult kolm jalga.
This table has only three legs.

In Estonian, unlike Finnish, we stick with the ADE unless we want to translate things like the above:

F: Hotellissa on uima-allas.
E: Hotellil on ujula.
The hotel has a pool.

but

Hotellissa on uima-allas.
Hotellis on ujula.
There is a pool in the hotel.

[Miumau]

Corghaicist already wrote a nice explanation, but I'd like to add one thing The adessive/inessive distinction can also be used to express roughly in and at in English. This is not related to possession though, but rather to physical location.

Hotellissa on uima-allas. There is a pool in the hotel. (Or possession: The hotel has a pool.)
Hotellilla on uima-allas. There is a pool at the hotel. (i.e. somewhere in the surroundings of the hotel)

The second sentence could also be understood as possession but for some kind of abstract "hotel" entity, not for a physical location, as in "The hotel (the hotel company) has a pool".