One has:
6 flow-thru style sensors (part # TST-507-FT-6-C)
One has:
6 RV cap style sensors (part # TST-507-RV-6-C)
When looking at the difference it appears the less expensive one has the flow through caps, the other doesn't.
IMO I'd think the flow through design would be the better choice, easier to add air if needed, and it's less expensive.
There are 24 hours in every day - it all depends on how you choose to use them.
Bruce & Jill Brown
2008 Kountry Star Pusher 3910