Double Ended metal halide lamps in either the 70w or 150w wattages use the same type of end connectors and are rougly the same size as a double ended halogen lamp - so similar that one will physically fit into the other's socket - but the two are VERY different. (250w and 400w double ended halide lamps use a different end connector which will not fit interchangeable with the halogen.)
NO, they cannot be used interchangeably.
The metal halide lamp requires a ballast and ignitor for proper operation. Putting a metal halide lamp into a normal halogen light fixture (installed and wired as such) will cause nothing... the lamp will not light or otherwise work, but it won't cause any actual damage.
Going the other way around, placing a halogen lamp into a metal halide fixture will either destroy the lamp from the ignitor pulse, or the lamp's presence will destroy the ignitor and possibly the capacitor in the ballast.
Some aquarists modify halogen fixtures to create DIY halide fixtures, but do not be fooled, the modifications include the ballasts and necessary components to do the job.