First, what do you mean with the difference between "blink" and "flash"? (The terms are nearly synonymous to me, so I'm just trying to understand the desired outcome--not trying to be picky about the word we use, so hope it doesn't appear that way!)
Second, if you are using Hubitat's stock Hue Bridge integration, it does not have a way to do this. Lots of bulb/dimmer/switch drivers in Hubitat don't, so this isn't unusual; it's not a "standard" command required by any Hubitat capability. That being said, some drivers do implement the "Flash" command, so it's become sort of a pseudo-standard and is available as a command you can run via standard actions in Rule Machine, for example. It's also an option in HSM, as you may have seen. But without this command available in the driver for your device, you could "fake it" with a series of repeated on/off actions in your rules (or any app).
With Hue in particular, a third issue is that they do not natively support an indefinite blink/flash. (Actually, it would be possible to install a series of rules on the Bridge via the API that can do this, but I'm not aware of any integration that does, and I just recently discovered enough about this myself to see that it would indeed be possible.) They do support a command that will make them fade up/down, basically blinking (but a slightly smoother transition), for about 30 seconds. My custom CoCoHue integration can send this command natively, but you could also do it directly to the Hue API yourself with a custom app or driver if you preferred. In my integration, this is done via the "Flash" command on Hubitat, so it would work with Rule Machine or HSM. But it still may not be exactly what you want.