What is the difference in the "Flesh" and the "Law?"
The law is either the Law of Moses, or else, it's the laws we devise ourselves, or someone else devises, which make us believe that keeping these laws, or trying to do so, will give us victory. It won't!
The "flesh" is the effort and ability of the individual, and I speak of education, motivation, intellect, talent, ability, etc. The idea is, when one resorts to law, he has nothing but the flesh to help him because the Holy Spirit will not get involved in such an effort. This leaves the person guaranteed of defeat.
Why is the "Flesh" incapable?
It is incapable because of the Fall that made it ineffective. Paul said, "And if Christ be in you, the body is dead because of sin; but the Spirit is life because of righteousness (Romans 8:10)."
Despite this, we Believers keep trying to do that which cannot be done and which was never meant to be done by us. God has a Way, and we must function in that Way, which will guarantee victory.
For the Believer to receive everything for which Christ died, which is Salvation for the soul and Sanctification for the Saint, all the Believer has to do is place his Faith entirely and totally in Christ and what Christ did for us at the Cross (Rom. 6:1-14; 1 Cor. 1:17-18, 23; 2:2; Gal. 6:14). When this is done, our Faith placed totally and completely in Christ and the Cross, then the Holy Spirit, Who is God, begins to do for us what we cannot do for ourselves. Paul said, "But if the Spirit of Him that raised up Jesus from the dead dwell in you, He that raised up Christ from the dead shall also quicken your mortal bodies by His Spirit that dwelleth in you.
This is "a living sacrifice, holy and pleasing to God!"