I was looking at some bullets on the SPS site. They list 2 different 180 gr Partitions, a SP (I assume that means soft point), and a "protected point". What's the difference? they both look like lead tipped bullets as far as I can tell.

The protected point is a flat nose , in 30 cal they were developed for 300 win mag so they could be seated long and not damage the tip

Lower BC but hell on game!

In bullet nomenclature SP can mean Spitzer or Spire Point.

This. The jacket comes all the way to the tip with a small flat nose, instead of a small cone of exposed lead tip on a SP style. Avoiding damage during feeding and from recoil in the magazine are the reasons for it.

Some have observed a tiny bit better accuracy with the protected point. That Nosler continues to produce them tells some kind of story.
Mule Deer, at one time commented that someone at Nosler had told him that the protected point took a little more effort to produce which might account for this phenomena. I hope my memory is accurate on that it can sometimes be selective.
In my 300 Win Mag, I did experience better accuracy. However to pointed version was/is pretty darn good. The rifle is a CLR that has had a M Forbes total makeover.
I have trialed them in my 300 Savage and they looked very good there, but settled on 150's for hunting.
I have had a long and happy history with Partitions. They've performed well on game in several rifles and calibers over many decades.

I tried the 180 gr Protected Point in a 300 WSM years ago and it was very accurate so there may be something to what you are saying.