In Relay GraphQL, connections and lists are both array-like, but they have different features. When should I use each?
Connections
- More powerful and flexible than simple lists.
 - Support pagination (forward and back), with cursors.
 - Fine-grained mutation support (eg. 
RANGE_ADD,RANGE_DELETE,NODE_DELETE, as described in the guide). - Requires a 
firstorlastargument in order to limit the size of the result set. - Has an 
edgesfield that provides a place to locate per-edge, edge-specific data. - A heavier-weight concept, requiring more work to define in the schema.
 
Lists
- Simple and lightweight.
 - No support for pagination (the entire list is always returned).
 - No special mutations features for prepending, appending etc (although it is a requested feature).
 
Which to use?
- Whenever you need pagination, you should use a connection.
 - If you need fine-grained control over mutations, you may choose to use a connection, even if you don't need pagination.
 - If you want all the items in a connection, you can use 
firstwith some large number. - If you want to expose a short list with minimal effort, use a simple list.
 
来源:https://stackoverflow.com/questions/33088119/when-should-i-use-a-relay-graphql-connection-and-when-a-plain-list