Let's say you're rendering a table. I'm assuming that's how visualizing this data would make sense.

Then you'll store your first response and store it as its and render the default table

Now when you get your latest response. You'll start comparing row and then column wise if there is difference then the rendered value should be surrounded with a tag to make it bold. Here's a rough code

Assuming a react app

function RenderRow({row, index, latest}){
  if(latest.length < index) {
     console.log("This should not be possible")
     return null
  }

  return <tr>
  {
    row.map((column, c_index) => {
      if(latest[index][c_index] === column){
         return <td>{column}</td>
      }
      return <td><b> {column} </b></td>
    })
  }
  </tr>
}


function TableBody({original, latest}) {

  return <tbody>
   {
      original.map((row, index) => 
         <RenderRow row={row} index={index} latest={latest}/>
      )
   }
  </tbody>
}

function RenderAll(){
  let original= [ {firstVal:'1.2'},{SecondVal:'3.2'}];

  let latest= [{firstVal:'1.2'},{SecondVal:'4.2'}]
  return <Table latest={latest} original={original}/>
}