Naruto Shippuden Episode 35

[Abdula]

Just to add my two cents. The villages are part of countries, specifically they are the primary military force of a country, the country is ruled by the feudal lord. So while the hokage may be able to make decisions about what missions ninjas take she is not the leader and there is a council of elders above her who make decisions. Tsunade is more of a general her mission is to protect and do what is in the village’s best interest but the village is there to protect the country so while she may be able to make some military decisions she is not involved in the politics.

I think the difference between ANBU and regular ninja though is that while all missions are assigned to ninja by the Hokage, ANBU missions don't necessarily have to be justified, or even reported, to the council since they may not always be in line with the public face of the villiage. Things like assassinations and infiltrations are probably not suited to be talked about in open council.

Yeah, that would be the difference, the anbu perform covert missions that the hokage would not necessarily want the public or the other villages to know about.