I don't play on Android but I already read about this.
When you tranfer your account from a IOS to a Android device, you will lose all the IOS features, mining, battle arena - tournaments, world event, dragon summoning (if TL ever starts one again), spell shop, trading portal, quest outpost, arctic isle - and all things from there, spin to win, storage, healing spring and boosted breed.
This is what I know
Some buildings on your island, will turn in to decor, like the spell shop, trading portal and probably the healing spring too.
If you have buildings on the mining island, probably or you will lose access to them or they desappear, or they will stay there but you cannot move them, I'm not sure, I'm supposing.
If you have things in storage, since Android doesn't have storage, you probably will lose them, if not, you only can use them or see them on a IOS device, don't know.
About the Artic Isle, or you will lose all you have there, or that will be saved on your data account like the storage, and you only can see or "use" them on a IOS device.
The last thing, all of the IOS dragons that you have, they will stay on your island, they are yours.
I recommend you to talk with Kooky or Maguar, they are the only ones that can answer to your question without any doubt, they and the players who already tranfer their account from a IOS to a Android device :P