Simplify the following text for a Grade 9 native English-speaking person.
Original: Although many of the islands ' largest hills including Ben Nevis , Carrantuohill , Scafell Pike and Snowdon are Marilyns , many other large hills such as Cairngorm , a number of Munros , and other well-known hills such as Bowfell , the Langdale Pikes and Carnedd Dafydd , are not Marilyns because they do not have sufficient relative height .
Simplified: Many of the largest hills are Marilyns , including Ben Nevis , Scafell Pike and Snowdon . On the other hand , many large hills , including some Munros , and other well-known hills are not Marilyns because they do not meet the relative height criterion .