There isn't much base to this other than fun.
Ever since ADTOE I have said, to my friends and myself, Systematic Chaos begins the bands Octavarium(coming full circle).
Systematic Chaos is their first album on a new label, made before they signed with roadrunner. Its production is considered Loud and Brickwalled which DT hasn't really had since WDADU. Which this album compares to as their 1st. Thats where the comparisons end though.
Black Cloud and Silver Linings had been hyped as a mix of epics with one of them being Learning to Live. Images was the first with their new singer which brought new life. Black Clouds was coincidentally named, due to MP deciding to leave, making the album have the opposite effect of losing life. Plus...They both have "and" in the title.
A Dramatic Turn of Events, you could say, continues the Images connection based on the structures of some songs. It introduces Mike Mangini healing the entity to breath life into it once again. Awake was when they had lost KM when they finished recording causing a wound to it. Again opposite effect. But, as Awake ends with a piano led ballad, Dramatic ends with a guitar led ballad, both somber.
Dream Theater has the sound of the snare, the chocolate cake, and rush bass. Some consider it good some not so much. Its aggressive and in your face brickwalled. Complete 180 of Falling Into Infinity. Although, they both have shorter songs. Illumination Theory is what Metropolis pt.2 was to FII.
The Astonishing (This one should be obvious), A full blown concept album with a setting, narrative, cast of characters, acts, visual, and novel. Scenes From A Memory, a safe concept with minimal characters and story, akin to a childrens book.
Now we have 6DOIT and the upcoming album. They've been saying it'll be interesting. And if Manginis ideas are used more, it'll be like Rudess first using his ideas in 6DoIT.
As I said above this is all for fun and something i thought was cool and interesting to notice.