At full power, the superlaser would probably not just destroy any rebel ship, but punch straight through, keep on going, and possibly take out one of their own Star Destroyers behind them.

Wave-Motion Gun: The Death Star II is armed with a cannon just as powerful as the first planet-destroyer, except this one only needs a few minutes to charge up and fire, though this could be from not charging to full power, as they are only shooting at ships.

Had it not been for the ewoks, the Rebellion would've been unable to get in.

Taught by Experience: No easily overlooked and exploitable exhaust ports this time.

Serial Escalation: Although the Death Star was not complete, it was bigger and far more powerful than the original Death Star.

Screw This, I'm Outta Here!: Once the Endor Shield array is destroyed and the Emperor is killed, Imperial crewmen, guards, stormtroopers, officers, and pilots begin to flee the doomed Death Star.

The new Canon sources have firmly set the diameter at 200km.

Retcon: Legends materials originally gave the second Death Star's diameter at 160km, before this was retconned to 900km.

As Luke, and then the Rebellion as a whole, learns, the second Death Star is fully armed and operational.

Obfuscating Disability: It's designed to look not-quite finished, with massive gaps in the superstructure (and technically speaking, it isn't actually finished by the opening of Return of the Jedi).

Deflector Shields: The new Death Star is protected by one, generated by a station on Endor.

However, it also served another purpose which involved luring the Rebel Alliance into a battle which would annihilate them once and for all. Similar to the first Death Star, this station was designed to terrorize planets and star systems. A partially complete space station that served as the successor to the original Death Star.

Star wars imperial lieutenant