It did end originally, it's stated in an article. The creators ended production on the show for good and it came back because Nickelodeon wanted more episodes.

SpongeBob and Adventure Time share a co-creator (Derek Drymon) and AT shares alot of the same writers as the former did in it's original run so AT is the spiritual successor to the first 3 seasons of Spongebob.

The show wasn't put on hiatus despite popular claim, it ended for a while (for good) and then it came back because of how merchandise was doing and Nickelodeon wanted more episodes.