What is the difference between founding day and national day?

The Kingdom of Saudi Arabia has adopted February 22 as an official holiday, by royal order, to celebrate the establishment of the Saudi state, under the name "Foundation Day", in addition to the Saudi National Day holiday that the Kingdom celebrates on the twenty-third of September every year, so what is the difference between the National Day and Saudi and founding day?

The Saudi Foundation Day differs from the National Day, but these two days remain of great importance

National day

This day is celebrated on the 23rd of September of each year, on the occasion of the announcement of the unification of the Saudi lands and the establishment of the modern Saudi state at the hands of the founding King Abdul Aziz, as the Saudi lands were unified on the 23rd of September of the year 1932 AD corresponding to the 17th of the month of Jumada al-Awwal for the year 1351 AH.

Founding day

This day is celebrated on the 22nd of February of each year, on the occasion of the first birth of the Saudi state, as Imam Muhammad bin Saud established the first Saudi state in the middle of the year 1139 AH corresponding to February of the year 1727 AD, specifically on the 22nd of February, and it was the capital of This state is Diriyah, and its constitution is the Holy Qur’an and the Sunnah of the Messenger of God, Muhammad, may God bless him and grant him peace, and it continued until the year 1233 AH (1818 CE).