I am new to the Wolfram Language and am trying to learn to read code. Below is a figure showing some expressions and the evaluation of those expressions.

I would expect (as it turns out, wrongly) that the expressions in lines 5 and 6 would give the same result, but they do not.

It seems to me that the argument seen by ToString in the two cases (5,6) should be the same and, thus, give the same result.

If one asserts that the argument seen by ToString in line 5 is '2+3' and in line 6 is 'Unevaluated[2+3]', then one would have to explain why in line 3 the List function does not get '2+3' as its argument which, apparently, it does not. Neither ToString nor List have Hold Attributes of any kind.

Any insights or suggested reading would be appreciated.