There's a great article over on Inverse Entertainment (I've never heard of them before either... a friend posted this on Facebook) that talks to David Mack's novel Desperate Hours, in which it deals with the issues of the supposed continuity violations between "The Cage" and Star Trek: Discovery.
If you don't know, in the novel, the Shenzhou and Enterprise meet up and Mack addresses the issues that many fans have regarding the seeming visual discrepancies between the two takes on Trek. The uniforms we see in Discovery are older and those from "The Cage" are being utilized on the Constitution-Class Starships. This, of course, has precedence with the uniforms seen in DS9 and Voyager being different than those in Next Generation.
As for the designs of the ship itself, while we don't know how old, but at the flashback at the beginning of "Battle at the Binary Stars," Captain Georgiou indicates Shenzhou is "old, but she gets us where we need to go." A quote from the novel, Spock thinks:
In the end, I don't need an in-universe explanation, because I see it as an extrapolation of future based upon where we are in 2017 as opposed to 1964. I respect and appreciate this is not a good enough answer for everyone, but I thought it was worth sharing.
If you don't know, in the novel, the Shenzhou and Enterprise meet up and Mack addresses the issues that many fans have regarding the seeming visual discrepancies between the two takes on Trek. The uniforms we see in Discovery are older and those from "The Cage" are being utilized on the Constitution-Class Starships. This, of course, has precedence with the uniforms seen in DS9 and Voyager being different than those in Next Generation.
As for the designs of the ship itself, while we don't know how old, but at the flashback at the beginning of "Battle at the Binary Stars," Captain Georgiou indicates Shenzhou is "old, but she gets us where we need to go." A quote from the novel, Spock thinks:
It was clear to him that the two ships had been designed and constructed in different eras, according to very different aesthetic standards. Such drastic changes in a short span of time were not unusual among the humans of Earth, though it had proved a constant source of bemusement among their Vulcan and Andorian allies.
In the end, I don't need an in-universe explanation, because I see it as an extrapolation of future based upon where we are in 2017 as opposed to 1964. I respect and appreciate this is not a good enough answer for everyone, but I thought it was worth sharing.