Simplify the following text for a Grade 5 native English-speaking person.
Original: The true hornets make up the genus Vespa and are distinguished from other vespines by the width of the vertex ( part of the head behind the eyes ) , which is proportionally larger in Vespa and by the anteriorly rounded gasters ( the section of the abdomen behind the wasp waist ) .
Simplified: The true hornets make up the genus Vespa . True hornets can be distinguished from other vespines by the form of their head .