What is the difference between Phone Unlock code vs Unblock Code

I have this Huawei 1611 ATT go phone. I got the phone unlocked from ATT, later switched to H2O Wireless and it worked smoothly.

This year I switched to Simple Mobile and after inserting new sim I was presented an option to key in NCK code. I have the new sim code and entered it which did not work. After multiple attempts phone is blocked.

If I insert the old H2O sim card I still get same message to 'Enter Unblock code'. I'm not sure if it is an issue with sim cards as I have PUK code and SIM code for both sims.

I also have Phone Unlock Code, that is also not working.

Can some one help me please with this Unblock Code?