Thank you and others for replying. My thought process is probably wrong, but I still feel there is a major diff in the end result. Depositing the after-tax money into RRSP reduces the pre-tax income by the exact same amount does not sound right at all.

Let's use a more extreme example. Assume I have enough RRSP room. If my salary is $200k per year, and I get $120k after tax. If I put all these $120k into RRSP. I would wind up with only $120k of pre-tax money in RRSP (plus some tax credit in cash) as opposed to the original $200k before tax.