The difference is...
the V1:
Stainless steel construction (brushed)
Top cap with air-channels cut
Adjustable 510 center pin
Silver plated brass contacts
Unique serial number
Laser etched logo and patterns
Spring-loaded firing switch
Reverse
threaded locking ring
Houses single 18350/18500/18650 battery
the V2:
Stainless steel construction (brushed)
Top cap with air-channels cut
Floating 510 center pin
Brass contacts
Unique serial number
Laser etched logo and patterns
Bottom plastic insulator
Spring-loaded firing switch
Locking ring is NOT reverse
threaded
Houses single 18350/18500/18650 battery