my question too. I put the two English sentences in google translate. For make things interesting it said siempre haces las cosas interesentas. For interesting things it was as the duo sentence. Looks like the addition of las makes the difference.
Yeah, I'm not sure why but the las is definitely important. If I wanted to say: you always make things interesting, I would probably say siempre haces interesantes las cosas but either one should be right