Fender Telecaster Neck Pickup, Lip Stick Style VS Open Cover.
Is there really any difference, absolutely there is, on all my custom hand would Tele neck pickups I use an open pickup cover.
Open covers produce more "poke" and punch. Not having a metal barrier across the top of the magnetic field opens up the treble response. It sounds clearer, brighter, and closer to a Strats neck tone. And they just give it a better look.
Lipstick-style covers alter the magnetic field, this results in a warmer, rounder tone with less high-end presence. They are known for a glassy, hollow, and slightly "compressed" or "smeared" tone.
When buying a lip stick style be sure you always buy the brass based ones because brass conducts eddy currents, this will have a warmer, rounder tone compared to modern nickel-silver covers.