If they are recognized as a legal tribe, the Chinooks can own a piece of land. For example, a benefit of owning land for some tribes has been that they have built a casino so that they can then earn money. Also, if somebody wanted to build on their land they would have to consult with the Chinooks first.
Tribes can also administer their own schools, courts, police forces and social programs.
The Chinooks have not been recognized as a tribe because the government says that they haven't existed as a continuous entity since making contact with whites along the Columbia River in 1811. They also say that the tribe hasn't had political authority since 1855 and has not formed a distinct geographical community since 1880. The government put the Chinooks on a reservation, and on that reservation the Chinooks gradually started to split up and became less like a community. Then the government took away the reservation land. So it's the government who took the land, and told them that they were not a legal tribe.