oracle adapter settings

Hi, when I was reading docs about rails + oracle I met 2 different ways to setup using oracle db in the database.yml file: for example,

development: adapter: oracle database: 192.168.0.100/orasid username: test password: test

and

development: adapter: oci host: 192.168.0.100/orasid username: test password: test

please, explain me what is the difference in ? Thanks.