As the Prince of Order, and generally accepted as "terrible Daedric prince afterthought," is Peryite actually a lesser daedra that rose to fill the role in Jyggalag's sudden, glaring absence?

Ive always seen Peryite and Jyggalag as embodying two different types of 'order'.
Jyggalag is a cold, mathematical, lifeless kind of order, he reminds me of Discworld's Auditors of Reality.
The kind of order that might see life as messy and inconvienently reversing entropy.

Peryite I see more as the natural order of things. You can see him and his plagues as a cleansing fire, strengthening the herd by taking out the weak.
I believe Peryite might care for life and mortals, might want to see them prosper in his own way, as opposed to Jyggalag who I see as indifferent and possibly an enemy of life.

That's a very small distinction of spheres though. Two different types of order, distinguished by motivation?

I wouldnt call it a small distinction.
Its like mother Earth and father Time, one is caring and natural, the other is cold and logical.
Its like the difference between order as envisioned by our ancestors and order as we see today in mathematics.
One is the way things should be, the other is the way things are and that doesnt care about your place in it.

Different facets of Order. Much like Kyne and Hircine are both Nature and Julianos and Herma are both Knowledge.