Between the two, the Pake Rum Runner has the nicer frameset.

Pake is built with CroMo tubing supplied by Tange. The Pure Cycle Original is made with Hi-Ten steel tubing. Test ride both if you can and see which one is more comfortable for you. For example my own go to bike is a Hi-Ten bike that I build up myself by converting a old 10 speed bike into a fixed gear single speed that rides really comfortably for me.

The Pake Rum Runner frame only (no fork) is currently $220 off of Soma's website. Whereas the entire bike built up from Pure Cycle's own website for their original fixed gear bike is $349. That should tell you the difference in the quality of the tubing and framesets. So, if the Pake is in good condition, it is probably the better deal if you are getting it as an entire bike.

Hope this helps.