Differences would be
1) Distributions from an S Corp ARE NOT SUBJECT TO SE TAX
2) Reg Require a Reasonable Salary- Only salary is subject to normal FICA/MedCare + Co Match
3) A separate Corporate tax return would be filed - unlike a single member LLC which is ignored for tax reportin ( disregarded entity/ Files a Schedule C or if Rental Schedule E...etc)

4) your projections showed no change is because your assumption -"under S corp he only pays SE tax on the distributions after deducting the reasonable salary" is completely incorrect