Long plate, smooth plate, ribbed plate?

What is the difference .....betweew them? I am looking at Telefunfen 12ax7's?
the long plate designation refers to a 17mm length plate structure (versus 14mm) inside the glass envelope while ribbed/smooth plate is the 14mm plate length either smooth or with a couple horizontal 'ribs' across the plates.

Sonically, any real Telefunken miniature nine-pin is great although long plate and ribbed plate seem to be in greater demand recently