Q: Relay vs Remote and Extending Airpot

OK I got an airport extreme base station - I want to extend the network to my backyard so I am going to buy an airport express.

Physically speaking, my extreme base station is in the front room, which has good range to the back porch, just not beyond my back porch where my yard is.

So I was planning on putting the airport express on my back porch.

What I'm unclear about is if I set this express as a remote base station, it will automatically connect to my main base station correct, since it would be within range of the main station, right? So I do NOT need a relay, meaning I don't need to buy 2 airport expresses? Correct or am I wrong here?