Comparing Powershell two excel files and repalce

I am new to Powershell, I need help comparing two excel files and need for it to look at the old file and get info from it and push it into the new file. If the ID is same. Here is an Idea of what I want it to do. Please help. Thank You.

#  

#If the old ID mathes the New ID# Push the Info1 and Info2

if (Old id = New id)
    {
    Push info1 and info2 into new file
    }
    
#If new id not avalable in the old 
elseif ( New Id not in Old)
    {
    Highlight Cell
    }
    
#If the ID from old not in the new then ignor and move on
else 
    {
    Ignor and move on
    }