Right yea. Concept is the same, implementation is different (and better).
Is proprietary lock-in better? (the hybrid drive would accelerate your dual-boot Windows partitions - the Fusion drive won't, and makes dual booting a PITA)
The word "better" means that it's subjective - and in many situations it's not "better".
The plants are beautiful inside the walled garden, aren't they?
In old hybrid drives, you have a small amount of SSD space that's used to cache regularly accessed data.
Those "old" drives are the latest tech

.
Like the OS would boot of it,
"Boot time" is really a nonsense measurement in this day and age.
My Win7 x64 laptop might reboot once or twice a month - it's usually just going between sleep and awake. Do I care if it takes one minute or two minutes to reboot - no!
Don't waste SSD space on files that might be accessed once or twice a month - let the drive decide how to make the best use of the SSD cache.
A hybrid drive sounds like it'd work better in practice, but I haven't ever heard many good things about it.
When I got my latest work laptop, I bought a Momentus XT 750 GB with my own money, and put the company drive in the static bag in a drawer.
I've bought Momentus XT 500 GB drives for two of my other laptops.
Money well spent - you've now heard "good things" about hybrid drives.
(I edited and extended my post, and several comments were made while doing that....)