"There is bread."
Translation:Det finnes brød.
They're pretty much the same. "det finnes" = "you will find", loosely. I can't really think of a context where i've only ever heard one alternative being used though. Det er kake på kjøkkenet, det finnes kake på kjøkkenet; or: det er mye vi ikke kan forklare, det finnes mye vi ikke kan forklare. I'm tempted to say it might be a regional thing.
No difference :) <i>Finnes/fins</i> are both spelling variations, but same meaning. Pronunciation is different tho, as "fins" is pronounced with only one syllable (as you would expect from the spelling).
You might also see finns, which I think is Swedish officially but it can sneak into Norwegian too...