Anchor rods and float rods are essentially the same thing, rods with threads on each end. The differences in what they are called are due to the different applications.
Float rods are used in conjunction with floating dock construction. They typcally run through a pipe on the interior of a float and hold together the wood panels on each end of the dock. Float rods are typically low-carbon steel, and hot-dip galvanized.
Anchor rods are embedded in concrete, and for marine construction purposes are often used to anchor bollards.