Both series have an animal-girl female lead and a (relatively) smart human male lead. There really isn't much else to add, but I honestly believe there is no need. Simply, if you liked one of those series, you could try the other one too.
There was something in Maoyuu Maou Yuusha that reminded me of Spice and Wolf a lot, the problem is: I'm not quite sure what it was. Maybe it had something to do with the medieval setting or powerful, non-human, ageless female lead or maybe with the semi-educational undertones (trading in Spice and Wolf and multitude of different things in Maoyuu Maou Yuusha). If you liked Spice and Wolf's uniqueness, then Maoyuu Maou Yuusha should prove itself to be a good read. On the other hand, if it's Maoyuu Maou Yuusha what you've read, then you should definitely try reading Spice and Wolf.
Both series feature a mischievous (and playful) female lead who not only loves the male lead, but also loves to teas him. If you liked the female lead in one of those two series then you could give the other one a try.