//...

const routes: Routes = [
  {
    path: 'admin', component: AdminComponent,
    children: [
      {path: 'login', component: LoginComponent},
      {path: 'products', component: ProductsComponent,  canActivate: [AuthGuard]}      
    ]
  },
  {
    path: '', component: WebsiteComponent,
    children: [
      { path: 'buy', component: BuyComponent }
    ]
  }
];

//...