Child Tax Credit versus Additional Child Tax Credit?

I have 2 children and in 2020, Turbo Tax showed a Child Tax Credit of $4000 (I assume $2000 for each child).  But in 2021, Turbo Tax labeled this as "Additional Child Tax Credit" with $4500 (and Child Tax Credit of $0).  I don't know why the child tax credit is listed differently between 2020 and 2021 ?  Did I do something wrong in Turbo Tax H&B?  Ages of fully dependent children at the end of 2021 are 13 and 17.

 

Questions are:

- is this expected / normal for 2021?

- we received the Covid relief money in 2021 (3 or 4 times) ... how did that affect my taxes?  I did not receive a tax form for that money I received.  should I have received a tax form for that money I received?

 

Thanks, Rob