The good Doctor's Fsmash uses special electricity that can also be used to vitalize people. This is the same power that flows through the pills and can cure any disease. This electricity contains special frequencies and feeds into our bodies' electrical network and energizes it at places and in frequencies however the good Doctor desires. At his health clinic this power is used to stabilize and heighten his patients' electric frequencies and thus significantly promoting good health in said patients' being.
This electric energy can also be given certain frequencies that are damaging to members of certain groups of entities. For example, The good Doctor has been known to use special frequencies that are damaging to viruses in order to rid people of the pestilences that said viruses bring.
But as above so below. The universe is made of an aether that serves as electric medium to frequencies just like the living beings that are part of the universe contain electric frequencies. So much like the good Doctor's electric frequencies can manipulate living beings in many ways it also can manipulate the universe of which those being are part in ways that are very similar to those in which it can manipulate living beings. Normally the good Doctor uses this ability to change his presence in such a way such that any environment that is being blessed with his presence changes into something that is fertile to the seeds of joy and happiness.
The good Doctor's Fsmash contains damaging electric frequencies. These cause great damage to any being unlucky enough to make contact with it. Hence it causes a lot of damage.
But due to the "as above so below" principle it also causes damage to the part of the universe it hits with. The universe is made of an aether containing electric frequencies as well, after all. This reality distorting power is what causes the knock back of the move.
So when the good Doctor's Fsmash connects with a target then it will both damage the frequencies of the target it connects with and thus inflicting great damage upon that target, and it will at the same time distort the electric frequencies of that part of the aether in which that target resides, causing a shockwave which rejects anything in it with great force and thereby causing the great knockback which this move is also known for.
The Chidori is a punch with an electrified fist.
I hope that this post will be enlightening to you as to what the differences are between these appearance-wise similar but otherwise in many important aspects vastly different moves.
