What is standard content projection vs. Multi-Slot Content Projection?

import { Component } from '@angular/core';

@Component({
  selector: 'app-card',
  standalone: true,
  template: '<div class="card-container">' +
    '  <div class="header">' +
    '    <ng-content select="header, [card-header]"></ng-content>' +
    '  </div>' +
    '  <div class="body">' +
    '    <ng-content></ng-content>' +
    '  </div>' +
    '  <div class="footer">' +
    '    <ng-content select=".card-footer"></ng-content>' +
    '  </div>' +
    '</div>'
})
export class CardComponent {}