The Old Covenant depended upon obedience - the new on faithfulness.
The Old Covenant has been “fulfilled” in Jesus - completed, in other words - so it no long applies. More than just diet and sacrifice were changed - the entire relationship between man and God is new. We now stand before God perfected in Jesus, with our sins as far as the East from the West. Moses could never say that!
All the difference in the world.
Both covenants depend on obedience and faith.
The promise is that he writes his Torah on our hearts. It was made to them as well as to us.
1John 2:
[3] And hereby we do know that we know him, if we keep his commandments.
[4] He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him.
[5] But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him.
[6] He that saith he abideth in him ought himself also so to walk, even as he walked.
[7] Brethren, I write no new commandment unto you, but an old commandment which ye had from the beginning. The old commandment is the word which ye have heard from the beginning.