If you are contrasting the 50mm non twin chamber fork with the 45 mm non twin chamber - they are very similar in design... On the other hand, the 50mm twin chamber is very different in design and takes a different approach to make them work well for a mix of trail riding, etc.
Les at LT-Racing (aka LTR) has a Husqvarna TXC510 with 50mm twin chamber marzocchi forks - we are best friends since childhood and actually
"share" the bike. Out of the box, these were set up as full on mx forks capable of pro level supercross...
He tamed them down and they are now quite plush. One difference/advantage of the twin chamber fork for off road work is that the oil level can be set much lower than the 45 or 50 non twin chamber fork.
jeff