What is the difference between MT/s and MHz when it comes to ram speed? And which one is better?

[Alex MR46]

I wanted to upgrade my laptop's ram since the current 8gb is really not cutting it for me. I always thought that ram speed is measured in MHz but then I saw this ram on amazon and it says that it's speed is 2666 MT/s. So I went to the task manager and there it said that my current ram speed is 2400MHz (it also said the same thing in BIOS). So here are the rams that I found online:

 

 

https://bit.ly/3qPp0v0    (Crucial 2666 MT/s SODIMMS CT8G4SFRA266 DDR4-minne, Grön 8 GB)  Price> ~30$

 

And:

 

https://bit.ly/3pLrhWP   (Crucial DDR4 8GB (1x8GB) SODIMM 2400MHz)  Price> ~50$

 

I want the speed of the new memory to match the speed of the memory I currently have on my laptop. 
I thought of buy the one with 2666MT/s speed since it is a lot cheaper. Does that speed match the speed of my current memory? and will there be a problem?

 

P.S. I don't have much experience with buying hardware. 

 

 

Here is a screen shot from the task manager. 

 

[Electronics Wizardy]

Basically all ram speed is measured in MTs, but often incorrectly labeled as MHz. So task manager is wrong, and it should say 1200MHz or 2400MTs.

 

Faster rated memory will work fine, and just run at the slower speed.

[porina]

MHz should be the real clock. MT/s is the marketing speed, but they mislabel it MHz. Real clock is half marketing speed.

[Alex MR46]

Thanks. So I will just go with the 2666MT/s. 

[merco]

actually this came out just a day ago maybe it will help you