Which is the proper translation for 委员会？ According to Xinhua News Agency, China Daily and other official media outlets of English language of China, 中央纪律检查委员会 is Central Commission for Discipline Inspection, but 中央政法委员会 is Committee of Polictical and Legal Affairs,发展和改革委员会 is National Development and Reform Commission,中央直属机关工作委员会 is Work Committee for Departments Directly Under the CPC Central Committee.

Commission and committee are both used to mean 委员会, what is the difference?
You are not the first person to wonder about the difference between 'commission and committee.'

https://www.quora.com/What-is-the-difference-between-commission-committee-and-council

Seems to me, in English, the difference is how they are formed: a committee is formed of volunteers, a commission is appointed. In China this distinction seems not so apparent, so they use 委员会 for both.

The original meaning of committ-ee was 'person to whom something is committed/entrusted'.
The original meaning of commission was 'authority entrusted to someone'.
So, actually, there is not much difference in English either! Both come from Latin 'committere'.