Does a hit destroy a unit in Axis and Allies 1942?
The receiver of the hits chooses which units to lose. In this example, the defender suffered two losses and would probably choose to lose one infantry and one tank (although he could, in theory take two tanks as losses).

The attacker suffered one hit, and will probably elect to lose the infantry.

That's why there is a so-called "infantry push mechanic" in the game, that encourages both sides to build (and lose) mainly infantry. Heavier units are for attack (not defense), to give your infantry an advantage over their infantry.