The Imperator-I was the first type of ISD brought in to replace the venators (Course then again, technicly the VSD did that but oh well) The Imperator-II was an upgrade of the Imperator-I, which sported more powerfull shields, stronger big guns (The four guns on each side of the command tower) and a few more guns overall. The visual changes were nonexistant.P.S. They are also called Imperial-I and Imperial-II Star Destroyers.
sigh...
For future, you should atleast read a few posts back before just jumping into a discussion...
read...
the class was OFFICIALY RENAMED imperial-I after the galactic purge
QUOTE FROM THE STARWARS WIKI: "Following the Great Jedi Purge and the establishment of the Galactic Empire, the model was renamed Imperial-class.[6]"
If your continuing to be stubborn...read this interesting peice of SW History...
The first ship of the first class was named Imperator. The second the Exactor (Darth Vaders first command ship).
If your going to go by historic tradition (class is named after first ship), and ignore Palpatines change then fine. Call it the Imperator-I Class...
HOWEVER the first ship of the second class was named IMPERIAL. If we go by historic tradition then wed have two classes:
Imperator class star destroyer
Imperial class star destroyer
The Imperator-II class does not, and never did exist in the Imperial Navy at any time.
and on another note you dont even seem to know what your talking about anyhow...
"...type of ISD..."
-uh...the ISD is a class of stardestroyer.
-the Victory class was designed to add more firepower to the Old Republics fleet during the mid clone wars. Specificily the VSD was the republics direct response to the Techno Union fleet of bulwark Mk I battlecruisers which escaped the blockade of Foerost. The VSD project was a collaberation of the rival companys Rindili and Kaut Drive Yards. The VSD was significantly more powerfull than the Venator Class but carried less starfighters into battle. (much less)
also...those 'big guns' you refer to were actually replaced in the ISD-II, by batteries of 8 barreled turbolasers in unarmored barbette mountings.
also the tractor beam targeting array between the sensor globes on the command tower was replaced with a communications tower