Source: p. 150 Top. Informal Logic: A Pragmatic Approach (2 ed 2008) by Douglas Walton. I edited the argument forms.
However, modus ponens is not the only form that the argument [in green, on the left] has. It also has this less specific form [in the red, on the right]:
Instead of representing [1.] as a conditional, we could also represent it as a simple proposition, A. Of course, representing it as a conditional would be more specific, but if we did represent it in the less specific form above, that would break no rule of logic we have, so far, required. And that form of argument is invalid. Even if both A and B are true, it is quite possible that C could be false, for all logic tells us.
The red argument purposes to rewrite green without any conditional statement, per the following:
For any given argument, the conditional that is formed by taking the conjunction (the "and-ing") of its premises as the antecedent and the conclusion of the argument as its consequent
[,] is the corresponding conditional to that argument.
But how does the green argument logically equal the red? One problem is the arguments' difference in conclusions: 3 does not equal 6.