Triode mode vs pento mode

I'm new to tube amps/preamps and have a very basic question. What's the difference between triode and pentomodes? Thanks.
It depends entirely on how well the output transformer is designed. However if you caught some of my comments earlier about the actual correct tap point of the screen taps, if the transformer is really set up correctly there will be no need for triode mode at all, since a correct UL tap will have the same linearity.

IMO this is a bet that most manufacturers of UL output transformers have missed, on account of the fact that so many have for decades now put the tap in the wrong place in order to avoid patent infringement. As a result many designers today don't even *know* that there was even a patent- they think the wrong place for the tap is actually the right place :)
Atmasphere -
Thank you for the response on ultralinear vs triode. That confirms my thoughts. Fwiw I got the Dyna's in triode mode and converted them back to ultrulinear. It was so much better I never went back. Later on I converted them back from 6550's to EL34's which I preferred on vintage Tannoys. I dont use them but they are nice to keep around.
I am new to tubes, but my experience so far with my Prima Luna amps (a Dialogue 4 and a Dialogue 7) is similar to Dover's. In triode, in my system, the PL's seem to lose resolution and dynamics. And the bass becomes less defined, even with my speakers crossed over at 80Hz into a sub.

It must be system dependent, because I've heard the PL's several times at shows, and I always preferred triode. But here at home, ultralinear is the clear winner.

Thanks a lot Atmasphere for sharing the knowledge.
Now I am so curious I want to get a Dyna myself to try out :)