what is the distinction between DetectIntent and MatchIntent

[my3sons]

Hello, 

I am working with the Dialogflow CX Python API and specifically the SessionsClient. I am working with both the DetectIntent and MatchIntent APIs to better understand how they work.

When I construct the DetectIntentRequest and MatchIntentRequest objects respectively, I am using the exact same values for the session, query_input, and query_params.

However, when I then execute those requests, I do get back results from the DetectIntent API that are what I expect, but the MatchIntent API always return no matches (see below example). The one somewhat weird thing is that the current_page value returned is not the current_page I sent in the request. The DetectIntent API does return the same current_page that I sent in the request FWIW. 

The API documentation is not overly helpful for me to troubleshoot this so I am hoping someone here understands better than me if I should be expecting the same intents to be returned from these 2 APIs or if there is a fundamental difference between them that would explain why I get results with one but not the other.

matches {
  match_type: NO_MATCH
  confidence: 0.3
}
current_page {
  name: "projects/blahblah/locations/us-central1/agents/dfe4ebab-b825-47ad-8630-302e85c83cfd/flows/00000000-0000-0000-0000-000000000000/pages/START_PAGE"
  display_name: "Start Page"
}