the difference between Old Cov and New Cov

salvation was always by grace through faith.

but, just as Jesus was under the law in the Old Cov, so all the believers were under the law in the Old Cov. ...this is why the New Cov is better; we're still believers saved by grace through faith, but now we have received the promises and the intimacy for which they only dreamed.

therefore, the difference is not salvation or grace through faith.

• the first difference is being free (out from under law).
• the second difference is the new nature and the Spirit inside you, and their perfect thoughts, emotions and desires (though these may be largely unconscious to you).
• the third difference is that (1) because of your freedom from law, (2) because of the thoughts, emotions and desires of the new creation and Spirit inside you (which may be largely unconscious to you), your conscious thoughts, feelings, desires and behavior can actually arise from that perfect new nature and the perfect Spirit inside of you. none of this was possible before.

i suggest to you this:

• to believe that you are free, really really free
• to believe you have a new nature and the Spirit lives in you, and both are 100% perfect, 100% in agreement, 100% in union  (despite what you do)
• believe that you constantly have a free choice to 'walk by the spirit' or to 'carry out the desire of the flesh'  ... and that you are perfectly loved, and that your spirit remains 100% perfect, 100% in agreement, 100% in union with God no matter which choice you make.