XFA24 :
I'm looking to expand my storage by another 1TB and I was looking at these two:
The sweet spot in terms of storage pricing right now is around 4 TB. You spend the least $ per GB at that size. Getting "only" 1 TB is pretty expensive in $ per GB.
What are the advantages and disadvantages of both drives? Is the extra $20+ be worth it for the Hybrid SSHD?, Will the Hybrid SSHD perform better in terms of access time, read and write?
To briefly sum up, the SSHD acts just like a HDD when it comes to writes, almost like a HDD at reading large files, like a SSD at reading small files (except the first couple times). So they're best for tasks which involve reading lots of the same small files (booting OS, loading programs and games).
How does the Hybrid SSHD even compare with my Samsung 850 PRO 256GB primary OS drive?
I would be storing my games onto that drive and would love to have it load faster and have increased reliability than the traditional drives such as 3.5" WDC Blues.
If you already have a SSD as your OS drive, don't bother with the SSHD. The SSD is substantially faster (more flash dies in parallel), and works for writes as well. A SATA SSD will hit over 500 MB/s sequential read/writes, about 30-70 MB/s 4k read/writes. From the testing I've done with SSHDs and HDDs cached with a small (16GB) SSD cache, they top out closer to 150 MB/s sequential, 15-30 MB/s 4k read. The only reason they're used is because HDDs typically only get about 0.75 - 1.5 MB/s 4k read/writes. SSHD writes go straight to the HDD so are likewise 0.75-1.5 MB/s for small files.
If you're worried about load speed for your games off the HDD, I'd find out if your motherboard supports Intel Smart Response Technology.
https://en.wikipedia.org/wiki/Smart_Response_Technology
https://www.intel.com/content/www/us/en/architecture-and-technology/smart-response-technology.html
https://www.pcworld.com/article/248828/how_to_setup_intel_smart_response_ssd_caching_technology.html
It'll let you set up a SSD (up to 64GB) as a cache for a HDD. Basically create your own SSHD. Just find a cheap, used small capacity SSD on Craigslist or eBay. Reliability doesn't really matter since it'll only be caching, not storing your data. Get a cheap 5400 RPM 3-4 TB HDD* and add the small SSD as a cache for it. That'll blow away a plain 7200 RPM HDD at everything except large sequential writes.
Since it sounds like you already have another HDD, Intel RST will allow you to use the same cheap SSD as cache for multiple HDDs. Just give each HDD a separate cache partition on the SSD. So it'll act like an upgrade for your existing HDD(s) as well.
* Avoid the 5400 RPM WD drives (Green, Blue, some Black). WD uses a very aggressive head parking timer on those drives, which parks the heads after about 10-15 seconds of inactivity. Unfortunately, every time there's a drive access and the heads are parked, your computer will pause for a split second while it waits for the heads to unpark. Mildly annoying during regular computer use, but deadly when gaming. Seagate and Toshiba (or Hitachi if you can still find them) don't have this problem.