Both terms are used in the spec and it appears that they are the same thing.

• Sec. 2.7 defines "response key" as
  • "By default a field’s response key in the response object will use that field’s name. However, you can define a different response key by specifying an alias."
• Sec. 5.3.2 uses "response name" without a definition.
• Sec. 6.3.2 uses "response key" with a definition in parentheses as
  • "the alias if defined, otherwise the field name."

Consistency would be appreciated. Or, if they are different, please add a definition for response name.

I see some implementations use "response name" and others use "response key". In the graphql-js codebase, only responseName is used.

• OverlappingFieldsCanBeMergedRule.ts#L86
• execute.ts#L409