In scripture testaments and covenants are the same thing. They both are contracts or agreements between entities.
The Scripture of Yahuwah is divided into two major sections by language. These sections are comprised of the Ibriy (Hebrew) scripture and the Greek scripture. These are the collections of books that make up the Scripture.
B’ereshiyth (Genesis) - Mal'akiy (Malachi) - 39 books
MattithYahuw (Matthew) - Revelation - 27 books
The testaments (covenants) are different systems of the laws Yahuwah applied to different dispensations (administrations) that stop and/or start in easily identifiable places. Before the Law of Mosheh (Moses) there were many covenants made that were not written down. There will be another testament put into place at the return of Yahushua that as yet is unnamed.
Ten Words (Commandments) - precepts in force from the days of creation. These precepts are in force today with love in faith instead of fear of the consequences being the reason for obedience. Shabbath was established to commemorate the creation. (B'ereshiyth 2:3-4, Shemot (Exodus) 31:16.)
Old Testament (Law of Mosheh) - ritual and ceremonial law came into force when Mosheh sprinkled the book of the law with the blood of bulls and goats. The Ten Words are included later. It had to be obeyed whether believed or not. (Exodus 24:8)
New Testament (Law of Grace) - came into force when the Testator died (Ibriym 9:16-17). This law is the Ten Words restated as the "Royal Law." (MattithYahuw [Matthew] 22:37-40) It must be obeyed through love and faith. (MattithYahuw 27:50, Markos (Mark) 15:37, Loukas (Luke) 23:46, and Yahuchanan (John) 19:30)
What the Testament of Yahuwah Really Is
C.F. "Buck" Castleberry