when choose Float or Number types in Oracle
FLOAT is just an alias for NUMBER datatype in Oracle. So you can choose any of them, as they are just the synonym of each other.
See the Oracle docs:
FLOAT [(p)]
A subtype of the NUMBER datatype having precision p. A FLOAT value isrepresented internally as NUMBER. The precision p can range from 1 to126 binary digits. A FLOAT value requires from 1 to 22 bytes.