set vs defineProperty

components.my-component.js

import Component from '@ember/component';
import { computed, set } from '@ember/object';
import { inject as service } from '@ember/service';

export default Component.extend({
  myService: service(),
  
  computeComponentProperties: computed('componentProp1', 'componentProp2', function() {
    const statement = `The computed properties on the component are <b>property1: "${this.componentProp1}"</b> and <b>property2: "${this.componentProp2}"</b>`;
    console.log(statement);
    return statement;
  }),
  
  init() {
    this._super(...arguments);
    
    // set properties on the component
    this.componentProp1 = this.property1;
    this.componentProp2 = this.property2;
    
    // set properties on the service
    this.myService.set('serviceProp1', this.property1);
    this.myService.set('serviceProp2', this.property2);
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: '`set` vs `defineProperty`'
});

services.my-service.js

import Service from '@ember/service';
import { computed } from '@ember/object';

export default Service.extend({
  computeServiceProperties: computed('serviceProp1', 'serviceProp2', function() {
    const statement = `The computed properties on the service are <b>property1: "${this.serviceProp1}"</b> and <b>property2: "${this.serviceProp2}"</b>`;
    console.log(statement);
    return statement;
  })
});

templates.application.hbs

<h1>{{appName}} Demo</h1>
<br>
<br>
{{my-component
	property1='hello'
  property2='world'
}}
<br>
<br>

templates.components.my-component.hbs

<p>{{{this.computeComponentProperties}}}</p>

<p>{{{this.myService.computeServiceProperties}}}</p>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}