Do you want non disruptive updates or do you need non disruptive upgrades?
First there is a bit of play on words going on here with needs vs. wants, as well as what is meant by non disruptive.
Regarding needs vs. wants, they are often used interchangeably particular in IT when discussing requirements or what the customer would like to have. The key differentiator is that a need is something that is required and somehow cost justified, or hopefully easier than a want item. A want or like to have item is simply that, its not a need however it could add value being a benefit although may be seen as discretionary.
There is also a bit of play on words with non disruptive updates or upgrades that can take on different meanings or assumptions. For example my Windows 7 laptop has automatic Microsoft updates enabled some of which can be applied while I work. On the other hand, some of those updates may be applied while I work however they may not take effect until I reboot or exit and restart an application.
This is not unique to Windows as my Ubuntu and Centos Linux systems can also apply updates, and in some cases a reboot might be required, same with my VMware environment. Lets not forget about applying new firmware to a server, or workstation, laptop or other device, along with networking routers, switches and related devices. Storage is also not immune as new software or firmware can be applied to a HDD or SSD, either by your workstation, laptop, server or storage system. Speaking of storage systems, they too have new software or firmware that gets updated.
The common theme here though is if the code (e.g. software, firmware, microcode, flash update, etc) can be applied non disruptive something known as non disruptive code load, followed by activation. With activation, the code may have been applied while the device or software was in use, however may need a reboot or restart. With non disruptive code activation, there should not be a disruption to what is being done when the new software takes effect.
This means that if a device supports non disruptive code load (NDCL) updates along with non disruptive code activation (NDCA), the upgrade can occur without disruption or having to wait for a reboot.
Which is better?
That depends, I want NDCA, however for many things I only need NDCL.
On the other hand, depending on what you need, perhaps it is both NDCL and NDCA, however also keep in mind needs vs. wants.
Ok, nuff said (for now).