JSFiddle - React, Tailwind, and code Playground

Using the $watch function to copy data.

HTML

<div ng-app="shippingApp" ng-controller="ShippingCtrl">
     <h4>Shipping Information</h4>

    <input type="text" ng-model="mailing.first">
    <br>
    <input type="text" ng-model="mailing.last">
    <br>
    <input type="text" ng-model="mailing.address1">
    <br>
    <input type="text" ng-model="mailing.city">
    <hr>
     <h4>Billing Information</h4>

    <input type="checkbox" ng-model="billing_same">Same as shipping
    <br>
    <input type="text" ng-model="billing.first">
    <br>
    <input type="text" ng-model="billing.last">
    <br>
    <input type="text" ng-model="billing.address1">
    <br>
    <input type="text" ng-model="billing.city">
</div>

JavaScript

var app = angular.module('shippingApp', []);

app.controller('ShippingCtrl', function ($scope) {
    $scope.mailing = {
        first: 'Jon',
        last: 'Doe',
        address1: '123 Main Street',
        city: ''
    };
    $scope.billing_same = false;

    $scope.$watch('billing_same', function () {
        if ($scope.billing_same) {
            $scope.billing = $scope.mailing;
        } else {
            $scope.billing = {};
        }
    });

});