Well observed, GGFreak.
As you mentioned, these different expressions mean the same thing: the player rolls additional dice in search of successes. Standardizing this text is a really good suggestion and I will do this in future updates.
Each die rolled in an attack can generate a hit and each hit is defended separately. This is explained in the section about Defense rolls:
Defense Roll: For each hit suffered, the enemy makes a Defense roll (1d6). Each success absorbs 1 hit, each failure causes 1 wound token.