I wondering what is the difference between Chris Boderick's Pick Clip and a thumb pick. They both look like the same thing.
The thumb pick is a pick that wraps around your thumb. The Pick Clip is a metal thing that goes on your thumb to hold a pick of users preference. Basically put, a Pick Clip is a customizable thumb pick.

In my opinion, the pick clip is more suited towards metal/shreddy stuff, being developed for the purpose of 8-finger tapping, retaining pinch harmonics, and using a pick shape that you like and a standard thumb pick is better in applications for any kind of finger picking type style. Just to restate, this is just how I see it, and I'm sure people use the picks in the opposite way of how I see it.

Hope this cleared the confusion up for you.
Universe UV777 Signed by Steve Vai
Prestige RG2027X with Bare Knuckle Aftermaths
RG7621 swirled
Prestige RG1420
The pick clip is for holding a pick when you aren’t picking. A thumb pick is for picking with your thumb and having it sound as loud as strings plucked with fingers.