PHP：return和echo之间的区别[重复]

Question

This question already has an answer here:

• What is the difference between PHP echo and PHP return in plain English? 13 answers
• Difference between echo and return in php? [closed] 5 answers

I'd like to know the difference in PHP when using either return or echo as reading on Laravel forums tends to contradict points made in other questions such as this:

Difference between echo and return in php?

If I have something like this:

/**
 * Generate an appropriate response given the details that were entered by the client
 *
 * @param array $intent
 * @return void
 */
public function generatePaymentResponse(array $intent)
{
    # Note that if your API version is before 2019-02-11, 'requires_action'
    # appears as 'requires_source_action'.
    if (
        $intent['status'] == 'requires_source_action' &&
        $intent['next_action']['type'] == 'use_stripe_sdk'
    ) {
        # Tell the client to handle the action

        echo json_encode([
            'requires_action' => true,
            'payment_intent_client_secret' => $intent['client_secret']
        ]);
    } else if ($intent['status'] == 'succeeded') {
        # The payment didn’t need any additional actions and completed!
        # Handle post-payment fulfillment
        echo json_encode([
            "success" => true
        ]);
    } else {
        http_response_code(500);
        echo json_encode(['error' => 'Invalid PaymentIntent status']);
    }
}

Why is this not the equivalent?

/**
 * Generate an appropriate response given the details that were entered by the client
 *
 * @param array $intent
 * @return void
 */
public function generatePaymentResponse(array $intent)
{
    # Note that if your API version is before 2019-02-11, 'requires_action'
    # appears as 'requires_source_action'.
    if (
        $intent['status'] == 'requires_source_action' &&
        $intent['next_action']['type'] == 'use_stripe_sdk'
    ) {
        # Tell the client to handle the action
        return response()->json([
            'requires_action' => true,
            'payment_intent_client_secret' => $intent['client_secret']
        ], 200);
    } else if ($intent['status'] == 'succeeded') {
        # The payment didn’t need any additional actions and completed!
        # Handle post-payment fulfillment
        return response()->json([
            'success' => true
        ], 200);
    } else {
        return response()->json([
            'error' => 'Invalid PaymentIntent status'
        ], 500);
    }
}

The script in the frontend is as follows:

<script src="https://js.stripe.com/v3/"></script>

<script>
    // Create a new Stripe client
    var stripe = Stripe('{{ config('services.stripe.key') }}');

    // Create a new instance of Elements
    var elements = stripe.elements();

    // Create a card element and bind it to a <div>
    var cardElement = elements.create('card');
    cardElement.mount('#card-element');

    // Store elements needed as variables
    var cardButton = document.getElementById('card-button');

    // Bind a click event to the card button
    cardButton.addEventListener('click', function(ev) {
      stripe.createPaymentMethod('card', cardElement)
      .then(function(result) {
        if (result.error) {
        var errorElement = document.getElementById('card-errors');
        errorElement.textContent = result.error.message;
        } else {
            // Otherwise send paymentMethod.id to your server (see Step 2)
            fetch('/confirm_payment', {
                method: 'POST',
                headers: { 
                  'Content-Type': 'application/json', 
                  'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
                },
                body: JSON.stringify({ payment_method_id: result.paymentMethod.id })
            }).then(function(result) {
                // Handle server response (see Step 3)
                result.json().then(function(json) {
                  handleServerResponse(json);
                })
            });
          }
      });
  });

function handleServerResponse(response) {
  if (response.error) {
    var errorElement = document.getElementById('card-errors');
    errorElement.textContent = result.error.message;
  } else if (response.requires_action) {
    // Use Stripe.js to handle required card action
    stripe.handleCardAction(
      response.payment_intent_client_secret
    ).then(function(result) {
      if (result.error) {
        var errorElement = document.getElementById('card-errors');
        errorElement.textContent = result.error.message;
      } else {
        // The card action has been handled
        // The PaymentIntent can be confirmed again on the server
        fetch('/confirm_payment', {
          method: 'POST',
          headers: { 
            'Content-Type': 'application/json',
            'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
          },
          body: JSON.stringify({ payment_intent_id: result.paymentIntent.id })
        }).then(function(confirmResult) {
          console.log(confirmResult);
          return confirmResult.json();
        }).then(handleServerResponse);
      }
    });
  } else {
        var errorElement = document.getElementById('card-errors');
        console.log(response);
  }
}

</script>

Why is it that when I use return nothing is returned by the console but with echo it is?

When I have previously used the axios library the server functions have always explicitly returned JSON and not echoed it.

</div>