WD Black 2TB Enterprise RE HDD x2 got different SMART metrics

Just recently I bought a WD Black 2TB enterprise RE HDD from a local IT wholesaler.
Called it HDDnew.(serial number bearing the last 4 digit: 6664, see the picture below)

Previously I also got an older WD Black 2TB enterprise RE HDD 2nd Hand from an online seller 2 years ago. Called HDDold.(serial number bearing the last 4 digit: 0526, see the picture below)

Now, I have 2 at the moment. I tested on cyrstaldiskinfo. To check on the SMART metrics/attributes.
HDDnew has got no issue. Cyrstaldiskinfo software checked and showed = GOOD.

Same goes with WD Lifeguard diagnostic, did an extended test = PASS. HDDnew was in good health.
The weird thing is the temperature spiked at 49-51 c while it was under WD diagnostic Extend test,
which I thought it was high.

Crystaldiskinfo immediately sent an alarm to notify me temp was really hot on the HDD.
I had to install an extra case fase to cool down HDDnew’s temp, but the best I could do was 49c temp.

The funny / odd thing is when I do a comparison, both HDDs are a bit different than each other in terms
SMART metrics/attributes. Is it normal?

Is there anything to worry about?

The difference are

  1. HDDnew is always running at 4-3 degrees higher then HDDold. Why?
  2. HDDnew has got a lot more SMART metrics/attributes than HDDold. Why?

Anyone care to comment?

Please see the attached picture below.

Thank you.