servo driver on a chip ?

Hi all,

A friend is just getting into CNC and wanted me to look for a
home-brew way to use servo motors.

There are servo drivers on a chip, but the one found is for postioning
servo's not step and direction use.

Is there a name for the two different technologies ?

both being servos is confusing.

Also, is there a chip, or a circuit or a PIC or AVR method of reading
the encoders and controlling the motors ?

Dave