The difference between apolloClient and apolloServer?

I am trying to install the offline GraphQL playground, however, I am using apolloClient. All the tutorials online use ApolloServerPluginLandingPageGraphQLPlayground with apolloServer. I have tried to look up the difference between the two but it doesn’t seem as obvious. Can anyone tell me what the differences are?

It is to my understanding that apolloClient allows for one to use more links, whereas, apolloServer comes pre built with default links. I could be wrong though.