Not sure about your blue drive. Spinning disks are only for storage which doesn't need speed. If it's an older drive that you filled up, that might be your problem. Or, because it's from 2010, it might just be performing like an 8yo drive.
As for your SSD, I think that might be behaving correctly.
https://www.cnet.com/products/samsung-840-evo/review/
Sequential read: Up to 540MBps
Sequential write: Up to 520MBps (250GB/500GB/750GB/1TB), and up to 410MBps (120GB)
First, you never get the "up to" speed. Don't even be mad if it doesn't get there. They say "up to" for a reason. Your only a bit behind the read speed, and by a similar margin the write speed. You got 328MBps which is a bit slower than the up to 410MBps. But check out Anands review.
https://www.anandtech.com/show/7173/samsung-ssd-840-evo-review-120gb-250gb-500gb-750gb-1tb-models-tested/8
If you scroll down to the incompressible sequential read/write for the 120GB 840evo, you'll see you get scores of 504/401. You should compare to these numbers, not the 540/410. If you should get 504/401 and you get 475/328, you really aren't that far off.
Do the normal things. Update firmware, make sure there is free space on the drive, etc. You have an older smaller evo drive paired with an older slower CPU. It's a bit slower than what others got, but it's not horribly slow(er).