Not so much better, slightly better type of NAND, but otherwise about the same specs overall, honestly can't say why you'd be seeing such a serious drop in performance. That said, if your motherboard supports NVMe, this drive is $10 more and 6x faster than what you just bought, if you can return the WD Blue and get the WD Black I would strongly advise it.

https://www.amazon.com/BLACK-SN750-500GB-Internal-Gaming/dp/B07MH2P5ZD

You might check and see if the WD Blue has a firmware update available, this may help performance issues.