TranslateModule与TranslateService

Question

我正在处理离子/角膜，看到我页面的module.ts文件导入了翻译模块

import { TranslateModule } from '@ngx-translate/core';
@NgModule({
  declarations: [
    MyHelpPage,
  ],
  imports: [
    IonicPageModule.forChild(MyHelpPage),
    TranslateModule.forChild()             //what does forChild mean ?
  ],
})
export class MyHelpPageModule { }

并且page.ts文件具有翻译服务

import { TranslateService } from '@ngx-translate/core';
@IonicPage()
@Component({
  selector: 'page-my-help',
  templateUrl: 'my-help.html',
})
export class MyHelpPage {

  constructor(public navCtrl: NavController, public navParams: NavParams,

    public translate: TranslateService, ) {
  }

  ionViewDidLoad() {
    console.log('ionViewDidLoad MyHelpPage');
  }

}

有什么区别？